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Harry T. Haigler - One of the best experts on this subject based on the ideXlab platform.
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Annexins V and XII Alter the Properties of Planar Lipid Bilayers Seen by Conductance Probes
2013Co-Authors: Yuri Sokolov, William S. Mailliard, Nghia Tranngo, Mario Isas, Hartmut Luecke, Harry T. Haigler, James E. HallAbstract:abstract Annexins are proteins that bind lipids in the presence of calcium. Though multiple functions have been proposed for Annexins, there is no general agreement on what Annexins do or how they do it. We have used the well-studied conductance probes nonactin, alamethicin, and tetraphenylborate to investigate how Annexins alter the functional properties of planar lipid bilayers. We found that Annexin XII reduces the nonactin-induced conductance to �30 % of its original value. Both negative lipid and �30 �M Ca 2 � are required for the conductance reduction. The mutant Annexin XIIs, E105K and E105K/K68A, do not reduce the nonactin conductance even though both bind to the membrane just as wild-type does. Thus, subtle changes in the interaction of Annexins with the membrane seem to be important. Annexin V also reduces nonactin conductance in nearly the same manner as Annexin XII. Pronase in the absence of Annexin had no effect on the nonactin conductance. But when added to the side of the bilayer opposite that to which Annexin was added, pronase increased the nonactin-induced conductance toward its pre-Annexin value. Annexins also dramatically alter the conductance induced by a radically different probe, alamethicin. When added to the same side of the bilayer as alamethicin, Annexin has virtually no effect, but when added trans to the alamethicin, Annexin dramatically reduces the asymmetry of the I-V curve and greatly slows the kinetics of one branch of the curve without altering those of the other. Annexin also reduces the rate at which the hydrophobic anion, tetraphenylborate, crosses the bilayer. These results suggest that Annexin greatly reduces the ability of small molecules to cross the membrane without altering the surface potential and that at least some fraction of the active Annexin is accessible to pronase digestion from the opposite side of the membrane. key words: ion channel • Annexin • nonactin • alamethicin • tetraphenylborat
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Annexin B12 is a sensor of membrane curvature and undergoes major curvature-dependent structural changes.
The Journal of biological chemistry, 2007Co-Authors: Torsten Fischer, Harry T. Haigler, Ralf LangenAbstract:Abstract The regulation of membrane curvature plays an important role in many membrane trafficking and fusion events. Recent studies have begun to identify some of the proteins involved in controlling and sensing the curvature of cellular membranes. A mechanistic understanding of these processes is limited, however, as structural information for the membrane-bound forms of these proteins is scarce. Here, we employed a combination of biochemical and biophysical approaches to study the interaction of Annexin B12 with membranes of different curvatures. We observed selective and Ca2+-independent binding of Annexin B12 to negatively charged vesicles that were either highly curved or that contained lipids with negative intrinsic curvature. This novel curvature-dependent membrane interaction induced major structural rearrangements in the protein and resulted in a backbone fold that was different from that of the well characterized Ca2+-dependent membrane-bound form of Annexin B12. Following curvature-dependent membrane interaction, the protein retained a predominantly α-helical structure but EPR spectroscopy studies of nitroxide side chains placed at selected sites on Annexin B12 showed that the protein underwent inside-out refolding that brought previously buried hydrophobic residues into contact with the membrane. These structural changes were reminiscent of those previously observed following Ca2+-independent interaction of Annexins with membranes at mildly acidic pH, yet they occurred at neutral pH in the presence of curved membranes. The present data demonstrate that Annexin B12 is a sensor of membrane curvature and that membrane curvature can trigger large scale conformational changes. We speculate that membrane curvature could be a physiological signal that induces the previously reported Ca2+-independent membrane interaction of Annexins in vivo.
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Annexins V and XII alter the properties of planar lipid bilayers seen by conductance probes.
Journal of General Physiology, 2000Co-Authors: Yuri Sokolov, William S. Mailliard, Nghia Tranngo, Mario Isas, Hartmut Luecke, Harry T. Haigler, James E. HallAbstract:Annexins are proteins that bind lipids in the presence of calcium. Though multiple functions have been proposed for Annexins, there is no general agreement on what Annexins do or how they do it. We have used the well-studied conductance probes nonactin, alamethicin, and tetraphenylborate to investigate how Annexins alter the functional properties of planar lipid bilayers. We found that Annexin XII reduces the nonactin-induced conductance to ∼30% of its original value. Both negative lipid and ∼30 μM Ca2+ are required for the conductance reduction. The mutant Annexin XIIs, E105K and E105K/K68A, do not reduce the nonactin conductance even though both bind to the membrane just as wild-type does. Thus, subtle changes in the interaction of Annexins with the membrane seem to be important. Annexin V also reduces nonactin conductance in nearly the same manner as Annexin XII. Pronase in the absence of Annexin had no effect on the nonactin conductance. But when added to the side of the bilayer opposite that to which Annexin was added, pronase increased the nonactin-induced conductance toward its pre-Annexin value. Annexins also dramatically alter the conductance induced by a radically different probe, alamethicin. When added to the same side of the bilayer as alamethicin, Annexin has virtually no effect, but when added trans to the alamethicin, Annexin dramatically reduces the asymmetry of the I-V curve and greatly slows the kinetics of one branch of the curve without altering those of the other. Annexin also reduces the rate at which the hydrophobic anion, tetraphenylborate, crosses the bilayer. These results suggest that Annexin greatly reduces the ability of small molecules to cross the membrane without altering the surface potential and that at least some fraction of the active Annexin is accessible to pronase digestion from the opposite side of the membrane.
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Annexins V and XII alter the properties of planar lipid bilayers seen by conductance probes.
eScholarship University of California, 2000Co-Authors: Sokolov Y, Luecke H, William S. Mailliard, Harry T. Haigler, Tranngo N, Isas M, James E. HallAbstract:Annexins are proteins that bind lipids in the presence of calcium. Though multiple functions have been proposed for Annexins, there is no general agreement on what Annexins do or how they do it. We have used the well-studied conductance probes nonactin, alamethicin, and tetraphenylborate to investigate how Annexins alter the functional properties of planar lipid bilayers. We found that Annexin XII reduces the nonactin-induced conductance to approximately 30% of its original value. Both negative lipid and approximately 30 microM Ca(2+) are required for the conductance reduction. The mutant Annexin XIIs, E105K and E105K/K68A, do not reduce the nonactin conductance even though both bind to the membrane just as wild-type does. Thus, subtle changes in the interaction of Annexins with the membrane seem to be important. Annexin V also reduces nonactin conductance in nearly the same manner as Annexin XII. Pronase in the absence of Annexin had no effect on the nonactin conductance. But when added to the side of the bilayer opposite that to which Annexin was added, pronase increased the nonactin-induced conductance toward its pre-Annexin value. Annexins also dramatically alter the conductance induced by a radically different probe, alamethicin. When added to the same side of the bilayer as alamethicin, Annexin has virtually no effect, but when added trans to the alamethicin, Annexin dramatically reduces the asymmetry of the I-V curve and greatly slows the kinetics of one branch of the curve without altering those of the other. Annexin also reduces the rate at which the hydrophobic anion, tetraphenylborate, crosses the bilayer. These results suggest that Annexin greatly reduces the ability of small molecules to cross the membrane without altering the surface potential and that at least some fraction of the active Annexin is accessible to pronase digestion from the opposite side of the membrane
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Annexins V and XII Alter the Properties of Planar Lipid Bilayers Seen by Conductance Probes
2000Co-Authors: Yuri Sokolov, William S. Mailliard, Nghia Tranngo, Mario Isas, Hartmut Luecke, Harry T. Haigler, James E. HallAbstract:abstract Annexins are proteins that bind lipids in the presence of calcium. Though multiple functions have been proposed for Annexins, there is no general agreement on what Annexins do or how they do it. We have used the well-studied conductance probes nonactin, alamethicin, and tetraphenylborate to investigate how Annexins alter the functional properties of planar lipid bilayers. We found that Annexin XII reduces the nonactin-induced conductance to �30 % of its original value. Both negative lipid and �30 �M Ca 2 � are required for the conductance reduction. The mutant Annexin XIIs, E105K and E105K/K68A, do not reduce the nonactin conductance even though both bind to the membrane just as wild-type does. Thus, subtle changes in the interaction of Annexins with the membrane seem to be important. Annexin V also reduces nonactin conductance in nearly the same manner as Annexin XII. Pronase in the absence of Annexin had no effect on the nonactin conductance. But when added to the side of the bilayer opposite that to which Annexin was added, pronase increased the nonactin-induced conductance toward its pre-Annexin value. Annexins also dramatically alter the conductance induced by a radically different probe, alamethicin. When added to the same side of the bilayer as alamethicin, Annexin has virtually no effect, but when added trans to the alamethicin, Annexin dramatically reduces the asymmetry of the I-V curve and greatly slows the kinetics of one branch of the curve without altering those of the other. Annexin also reduces the rate at which the hydrophobic anion, tetraphenylborate, crosses the bilayer. These results suggest that Annexin greatly reduces the ability of small molecules to cross the membrane without altering the surface potential and that at least some fraction of the active Annexin is accessible to pronase digestion from the opposite side of the membrane. key words
W Gibb - One of the best experts on this subject based on the ideXlab platform.
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Distribution of Annexin I and II in term human fetal membranes, decidua and placenta
Placenta, 1996Co-Authors: M Sun, Y Liu, W GibbAbstract:Annexin I and II are calcium binding proteins implicated in the regulation of a number of cellular functions, including secretory processes, prolactin release and prostaglandin, formation. The cellular distribution of these proteins was examined in human term placenta, fetal membranes (amnion and chorion laeve) and decidua using immunohistochemistry. Annexin I was found in amnion epithelial cells and chorion laeve trophoblast but not in decidua, and was located in the syncytiotrophoblast cells of placenta. Annexin II and Annexin II light-chain were located, in the amnion epithelial cells, the cells of the mesenchymal layer between the amnion and chorion laeve, chorion laeve trophoblast and endothelial cells lining the blood vessels in the decidua. In contrast to Annexin I, Annexin II was located in the villous core and not the syncytiotrophoblast cells in the placenta. There was no apparent change in the distribution of these Annexins during labour. These findings indicate that the cellular distribution of these Annexins is different, and may be an imporant consideration when examining their synthesis or action in tissues and in vitro with mixed cell populations and tissue homogenates.
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Distribution of Annexin I and II in term human fetal membranes, decidua and placenta.
Placenta, 1996Co-Authors: M Sun, Y Liu, W GibbAbstract:Annexin I and II are calcium binding proteins implicated in the regulation of a number of cellular functions, including secretory processes, prolactin release and prostaglandin formation. The cellular distribution of these proteins was examined in human term placenta, fetal membranes (amnion and chorion laeve) and decidua using immunohistochemistry. Annexin I was found in amnion epithelial cells and chorion laeve trophoblast but not in decidua, and was located in the syncytiotrophoblast cells of placenta. Annexin II and Annexin II light-chain were located in the amnion epithelial cells, the cells of the mesenchymal layer between the amnion and chorion laeve trophoblast and endothelial cells lining the blood vessels in the decidua. In contrast to Annexin I, Annexin II was located in the villous core and not the syncytiotrophoblast cells in the placenta. There was no apparent change in the distribution of these Annexins during labour. These findings indicate that the cellular distribution of these Annexins is different, and may be an important consideration when examining their synthesis or action in tissues and in vitro with mixed cell populations and tissue homogenates.
Volker Gerke - One of the best experts on this subject based on the ideXlab platform.
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Annexin A1 and A2: roles in retrograde trafficking of Shiga toxin
PloS one, 2012Co-Authors: Lionel Tcatchoff, Volker Gerke, Sofia Andersson, Audrun Utskarpen, Tove Irene Klokk, Sigrid S. Skånland, Sascha Pust, Kirsten SandvigAbstract:Annexins constitute a family of calcium and membrane binding proteins. As Annexin A1 and A2 have previously been linked to various membrane trafficking events, we initiated this study to investigate the role of these Annexins in the uptake and intracellular transport of the bacterial Shiga toxin (Stx) and the plant toxin ricin. Once endocytosed, both toxins are retrogradely transported from endosomes to the Golgi apparatus and the endoplasmic reticulum before being targeted to the cytosol where they inhibit protein synthesis. This study was performed to obtain new information both about toxin transport and the function of Annexin A1 and Annexin A2. Our data show that depletion of Annexin A1 or A2 alters the retrograde transport of Stx but not ricin, without affecting toxin binding or internalization. Knockdown of Annexin A1 increases Golgi transport of Stx, whereas knockdown of Annexin A2 slightly decreases the same transport step. Interestingly, Annexin A1 was found in proximity to cytoplasmic phospholipase A2 (cPLA2), and the basal as well as the increased Golgi transport of Stx upon Annexin A1 knockdown is dependent on cPLA2 activity. In conclusion, Annexin A1 and A2 have different roles in Stx transport to the trans-Golgi network. The most prominent role is played by Annexin A1 which normally works as a negative regulator of retrograde transport from the endosomes to the Golgi network, most likely by complex formation and inhibition of cPLA2.
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Annexin A1 is a new functional linker between actin filaments and phagosomes during phagocytosis.
Journal of Cell Science, 2011Co-Authors: Devang M. Patel, Volker Gerke, Syed Furquan Ahmad, Dieter G. Weiss, Sergei A. KuznetsovAbstract:Remodelling of the actin cytoskeleton plays a key role in particle internalisation and the phagosome maturation processes. Actin-binding proteins (ABPs) are the main players in actin remodelling but the precise role of these proteins in phagocytosis needs to be clarified. Annexins, a group of ABPs, are known to be present on phagosomes. Here, we identified Annexin A1 as a factor that binds to isolated latex bead phagosomes (LBPs) in the presence of Ca 2+ and facilitates the F-actin–LBP interaction in vitro. In macrophages the association of endogenous Annexin A1 with LBP membranes was strongly correlated with the spatial and temporal accumulation of F-actin at the LBP. Annexin A1 was found on phagocytic cups and around early phagosomes, where the F-actin was prominently concentrated. After uptake was completed, Annexin A1, along with F-actin, dissociated from the nascent LBP surface. At later stages of phagocytosis Annexin A1 transiently concentrated only around those LBPs that showed transient F-actin accumulation (‘actin flashing’). Downregulation of Annexin A1 expression resulted in impaired phagocytosis and actin flashing. These data identify Annexin A1 as an important component of phagocytosis that appears to link actin accumulation to different steps of phagosome formation.
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Annexins: linking Ca^2+ signalling to membrane dynamics
Nature Reviews Molecular Cell Biology, 2005Co-Authors: Volker Gerke, Carl E Creutz, Stephen E. MossAbstract:Eukaryotic cells contain various Ca^2+-effector proteins that mediate cellular responses to changes in intracellular Ca^2+ levels. A unique class of these proteins — Annexins — can bind to certain membrane phospholipids in a Ca^2+-dependent manner, providing a link between Ca^2+ signalling and membrane functions. By forming networks on the membrane surface, Annexins can function as organizers of membrane domains and membrane-recruitment platforms for proteins with which they interact. These and related properties enable Annexins to participate in several otherwise unrelated events that range from membrane dynamics to cell differentiation and migration. Annexins are a multigene family of Ca^2+-regulated proteins that are characterized by a unique Ca^2+- and membrane-binding module — the Annexin core domain. This core domain enables Ca^2+-bound Annexins to peripherally dock onto membranes that contain negatively charged phospholipids. Each Annexin contains a second, highly varible region — the N-terminal interaction domain. It harbours binding sites for cytoplasmic protein ligands that can be targeted to membranes through the Annexin-core-mediated phospholipid interaction. Membrane-bound Annexins can form lateral self-assemblies that affect the mobility and organization of membrane lipids. Such activities probably regulate membrane-related processes like membrane-domain organization and membrane transport in endocytosis and exocytosis. Interfering with intracellular Annexin function, by overexpressing mutants or by using RNA-interference-mediated downregulation, has different effects depending on the Annexin being targeted. These include effects on actin assemblies at cellular membranes, the organization of endosomal subcompartments, Ca^2+-regulated exocytosis and midbody formation during cytokinesis. Some Annexins can also occur extracellularly and can have functions outside cells. Their release is not fully understood, but probably follows non-classical secretion pathways. Extracellular Annexin functions that have been substantiated by mouse knockout models are anti-inflammatory and fibrinolytic activities. These are probably mediated through specific cell-surface interactions with chemoattractant receptors on cells of the immune system and key enzymes of the fibrinolytic cascade, respectively.
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Interactions of Benzodiazepine Derivatives with Annexins
The Journal of biological chemistry, 1998Co-Authors: Andreas Hofmann, Volker Gerke, Céline Raguénès-nicol, Françoise Russo-marie, Anita Lewit-bentley, Achim Escherich, Jörg Benz, Luis Moroder, Robert HuberAbstract:Human Annexins III and V, members of the Annexin family of calcium- and membrane-binding proteins, were complexed within the crystals with BDA452, a new 1,4-benzodiazepine derivative by soaking and co-crystallization methods. The crystal structures of the complexes were analyzed by x-ray crystallography and refined to 2.3- and 3.0-A resolution. BDA452 binds to a cleft which is located close to the N-terminus opposite to the membrane binding side of the proteins. Biophysical studies of the interactions of various benzodiazepine derivatives with Annexins were performed to analyze the binding of benzodiazepines to Annexins and their effects on the Annexin-induced calcium influx into phosphatidylserine/phosphatidylethanolamine liposomes. Different effects were observed with a variety of benzodiazepines and different Annexins depending on both the ligand and the protein. Almost opposite effects on Annexin function are elicited by BDA250 and diazepam, its 7-chloro-derivative. We conclude that benzodiazepines modulate the calcium influx activity of Annexins allosterically by stabilizing or destabilizing the conducting state of peripherally bound Annexins in agreement with suggestions by Kaneko (Kaneko, N., Ago, H., Matsuda, R., Inagaki, E., and Miyano, M. (1997) J. Mol. Biol., in press).
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localization of five Annexins in j774 macrophages and on isolated phagosomes
Journal of Cell Science, 1997Co-Authors: Maria Diakonova, Jean-pierre Liautard, G Van Der Vusse, J. Ernst, Volker Gerke, Gareth GriffithsAbstract:Annexins are a family of structurally related proteins which bind phospholipids in a calcium-dependent manner. Although the precise functions of Annexins are unknown, there is an accumulating set of data arguing for a role for some of them in vesicular transport and, specifically, in membrane-membrane or membrane-cytoskeletal interactions during these processes. Here we describe our qualitative and quantitative analysis of the localization of Annexins I-V in J774 macrophages that had internalized latex beads, both with and without IgG opsonization. Our results show that whereas all these Annexins are present on both the plasma membrane and on phagosomes, the localization on other organelles differs. Annexins I, II, III and V were detected on early endosomes, while only Annexin V was seen on late endocytic organelles and mitochondria. Annexins I and II distributed along the plasma membrane non-uniformly and co-localized with F-actin at the sites of membrane protrusions. We also investigated by western blot analysis the association of Annexins with purified phagosomes isolated at different time-points after latex bead internalization. While the amounts of Annexins I, II, III and V associated with phagosomes were similar at all times after their formation, the level of Annexin IV was significantly higher on older phagosomes. Whereas Annexins I, II, IV and V could be removed from phagosome membranes with a Ca2+ chelator they remained membrane bound under low calcium conditions. In contrast, Annexin III was removed under these conditions and needed a relatively high Ca2+ concentration to remain phagosome bound. Because of their purity and ease of preparation we suggest that phagosomes are a powerful system to study the potential role of Annexins in membrane traffic.
Stephen E. Moss - One of the best experts on this subject based on the ideXlab platform.
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Annexins: linking Ca^2+ signalling to membrane dynamics
Nature Reviews Molecular Cell Biology, 2005Co-Authors: Volker Gerke, Carl E Creutz, Stephen E. MossAbstract:Eukaryotic cells contain various Ca^2+-effector proteins that mediate cellular responses to changes in intracellular Ca^2+ levels. A unique class of these proteins — Annexins — can bind to certain membrane phospholipids in a Ca^2+-dependent manner, providing a link between Ca^2+ signalling and membrane functions. By forming networks on the membrane surface, Annexins can function as organizers of membrane domains and membrane-recruitment platforms for proteins with which they interact. These and related properties enable Annexins to participate in several otherwise unrelated events that range from membrane dynamics to cell differentiation and migration. Annexins are a multigene family of Ca^2+-regulated proteins that are characterized by a unique Ca^2+- and membrane-binding module — the Annexin core domain. This core domain enables Ca^2+-bound Annexins to peripherally dock onto membranes that contain negatively charged phospholipids. Each Annexin contains a second, highly varible region — the N-terminal interaction domain. It harbours binding sites for cytoplasmic protein ligands that can be targeted to membranes through the Annexin-core-mediated phospholipid interaction. Membrane-bound Annexins can form lateral self-assemblies that affect the mobility and organization of membrane lipids. Such activities probably regulate membrane-related processes like membrane-domain organization and membrane transport in endocytosis and exocytosis. Interfering with intracellular Annexin function, by overexpressing mutants or by using RNA-interference-mediated downregulation, has different effects depending on the Annexin being targeted. These include effects on actin assemblies at cellular membranes, the organization of endosomal subcompartments, Ca^2+-regulated exocytosis and midbody formation during cytokinesis. Some Annexins can also occur extracellularly and can have functions outside cells. Their release is not fully understood, but probably follows non-classical secretion pathways. Extracellular Annexin functions that have been substantiated by mouse knockout models are anti-inflammatory and fibrinolytic activities. These are probably mediated through specific cell-surface interactions with chemoattractant receptors on cells of the immune system and key enzymes of the fibrinolytic cascade, respectively.
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The Annexins
Genome Biology, 2004Co-Authors: Stephen E. Moss, Reg O MorganAbstract:Annexins are traditionally thought of as calcium-dependent phospholipid-binding proteins, but recent work suggests a more complex set of functions. More than a thousand proteins of the Annexin superfamily have been identified in major eukaryotic phyla, but Annexins are absent from yeasts and prokaryotes. The unique Annexin core domain is made up of four similar repeats approximately 70 amino acids long, each of which usually contains a characteristic 'type 2' motif for binding calcium ions. Animal and fungal Annexins also have non-homologous amino-terminal domains of varying length and sequence, which are responsible for the distinct localizations and specialized functions of the proteins through post-translational modification and binding to other proteins. Annexins interact with various cell-membrane components that are involved in the structural organization of the cell, intracellular signaling by enzyme modulation and ion fluxes, growth control, and they can act as atypical calcium channels. Analysis of site-specific conservation in the core domain suggests a role for certain buried residues in the calcium-channel activity of vertebrate Annexins and in the structural stability of their core domains. Evolutionarily significant differences between subfamilies are preferentially localized to accessible sites on the protein surface that determine membrane binding and interactions with cytosolic proteins.
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Annexins in the secretory pathway.
Cellular and Molecular Life Sciences, 1997Co-Authors: S. R. Donnelly, Stephen E. MossAbstract:Among the multiplicity of roles suggested for proteins of the Annexin family, those implicating these proteins in regulated exocytosis remain among the most convincing. Studies in this area of Annexin biology have focused on Annexin II, which because of its unusually low Ca2+-requirement for phospholipid-binding has many of the requisite properties of a membrane fusogenic Ca2+ sensor. Other Annexins are also good candidates for exocytotic mediators, especially Annexins I and VII, which have strong vesicle-aggregating activities. In contrast, Annexin VI appears to block vesicle aggregation, perhaps acting as a negative regulator of exocytosis. In this review, we consider the evidence for and against Annexins having functions in the secretory pathway.
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Identification and partial sequence analysis of novel Annexins in Lytechinus pictus oocytes.
Biochemical Journal, 1994Co-Authors: Wen-jun Shen, J. Avery, N F Totty, J. Justin Hsuan, Michael Whitaker, Stephen E. MossAbstract:The Annexins are a major class of calcium-binding proteins with unknown functions. In an attempt to define novel model systems in which to study members of the Annexin family, we have investigated the expression of Annexins in eggs from the sea urchin Lytechinus pictus. Western blot analysis of L. pictus eggs using antisera raised against human Annexins I, V and VI revealed the presence of immunoreactive proteins of approximately 34 kDa, 35 kDa and 68 kDa respectively. The sea urchin Annexins behaved similarly to their mammalian counterparts, both during purification and in their ability to bind calcium-dependently to anionic phospholipids. Of the three sea urchin Annexins, the 34 kDa form was most abundant, yielding sufficient quantities for peptide microsequencing. The amino acid sequences derived in this way showed the L. pictus Annexin to be closely related both to mammalian Annexin I and to Annexins IX, X and XII from Drosophila and Hydra. However, N-terminal sequence from the L. pictus Annexin showed it to be a novel member of the Annexin super-gene family. The results are interesting in view of the complex evolution of the Annexin gene family, and also point to the potential usefulness of echinoderm eggs as a model system in which to study Annexin function.
M Sun - One of the best experts on this subject based on the ideXlab platform.
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Distribution of Annexin I and II in term human fetal membranes, decidua and placenta
Placenta, 1996Co-Authors: M Sun, Y Liu, W GibbAbstract:Annexin I and II are calcium binding proteins implicated in the regulation of a number of cellular functions, including secretory processes, prolactin release and prostaglandin, formation. The cellular distribution of these proteins was examined in human term placenta, fetal membranes (amnion and chorion laeve) and decidua using immunohistochemistry. Annexin I was found in amnion epithelial cells and chorion laeve trophoblast but not in decidua, and was located in the syncytiotrophoblast cells of placenta. Annexin II and Annexin II light-chain were located, in the amnion epithelial cells, the cells of the mesenchymal layer between the amnion and chorion laeve, chorion laeve trophoblast and endothelial cells lining the blood vessels in the decidua. In contrast to Annexin I, Annexin II was located in the villous core and not the syncytiotrophoblast cells in the placenta. There was no apparent change in the distribution of these Annexins during labour. These findings indicate that the cellular distribution of these Annexins is different, and may be an imporant consideration when examining their synthesis or action in tissues and in vitro with mixed cell populations and tissue homogenates.
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Distribution of Annexin I and II in term human fetal membranes, decidua and placenta.
Placenta, 1996Co-Authors: M Sun, Y Liu, W GibbAbstract:Annexin I and II are calcium binding proteins implicated in the regulation of a number of cellular functions, including secretory processes, prolactin release and prostaglandin formation. The cellular distribution of these proteins was examined in human term placenta, fetal membranes (amnion and chorion laeve) and decidua using immunohistochemistry. Annexin I was found in amnion epithelial cells and chorion laeve trophoblast but not in decidua, and was located in the syncytiotrophoblast cells of placenta. Annexin II and Annexin II light-chain were located in the amnion epithelial cells, the cells of the mesenchymal layer between the amnion and chorion laeve trophoblast and endothelial cells lining the blood vessels in the decidua. In contrast to Annexin I, Annexin II was located in the villous core and not the syncytiotrophoblast cells in the placenta. There was no apparent change in the distribution of these Annexins during labour. These findings indicate that the cellular distribution of these Annexins is different, and may be an important consideration when examining their synthesis or action in tissues and in vitro with mixed cell populations and tissue homogenates.