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Jeetain Mittal - One of the best experts on this subject based on the ideXlab platform.
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computational modeling highlights the role of the disordered formin homology 1 domain in profilin actin transfer
FEBS Letters, 2018Co-Authors: Brandon Gregory Horan, Gül H Zerze, Dimitrios Vavylonis, Youngchan Kim, Jeetain MittalAbstract:Formins accelerate actin polymerization, assumed to occur through flexible Formin Homology 1 (FH1) domain-mediated transfer of profilin-actin to the barbed end. To study FH1 properties and address sequence effects, including varying length/distribution of profilin-binding proline-rich motifs, we performed all-atom simulations of a set of representative FH1 domains of formins: mouse mDia1 and mDia2, budding yeast Bni1 and Bnr1, and fission yeast Cdc12, For3, and Fus1. We find FH1 has flexible regions between high-propensity polyproline helix regions. A coarse-grained model retaining sequence specificity, assuming rigid polyproline segments, describes their size. Multiple bound Profilins or profilin-actin complexes expand mDia1-FH1, which may be important in cells. Simulations of the barbed end bound to Bni1-FH1-FH2 dimer show that the leading FH1 can better transfer profilin or profilin-actin, with decreasing probability as the distance from FH2 increases.
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computational modeling highlights disordered formin homology 1 domain s role in profilin actin transfer
bioRxiv, 2018Co-Authors: Brandon Gregory Horan, Gül H Zerze, Dimitrios Vavylonis, Youngchan Kim, Jeetain MittalAbstract:Formins accelerate actin polymerization, assumed to occur through flexible FH1 domain mediated transfer of profilin-actin to the barbed end. To study FH1 properties and address sequence effects including varying length/distribution of profilin-binding proline-rich motifs, we performed all-atom simulations of mouse mDia1, mDia2; budding yeast Bni1, Bnr1; fission yeast Cdc12, For3, and Fus1 FH1s. We find FH1 has flexible regions between high propensity polyproline helix regions. A coarse-grained model retaining sequence-specificity, assuming rigid polyproline segments, describes their size. Multiple Profilins and profilin-actin complexes can simultaneously bind, expanding mDia1-FH1, which may be important in cells. Simulations of the barbed end bound to Bni1-FH1-FH2 dimer show the leading FH1 can better transfer profilin or profilin-actin, having decreasing probability with increasing distance from FH2.
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Dataset for: Computational modeling highlights disordered Formin Homology 1 domain's role in profilin-actin transfer
2018Co-Authors: Brandon Gregory Horan, Gül H Zerze, Young C. Kim, Dimitrios Vavylonis, Jeetain MittalAbstract:Formins accelerate actin polymerization, assumed to occur through flexible FH1 domain mediated transfer of profilin-actin to the barbed end. To study FH1 properties and address sequence effects including varying length/distribution of profilin-binding proline-rich motifs, we performed all-atom simulations of mouse mDia1, mDia2; budding yeast Bni1, Bnr1; fission yeast Cdc12, For3, and Fus1 FH1s. We find FH1 has flexible regions between high propensity polyproline helix regions. A coarse-grained model retaining sequence-specificity, assuming rigid polyproline segments, describes their size. Multiple bound Profilins or profilin-actin complexes expand mDia1-FH1, which may be important in cells. Simulations of the barbed end bound to Bni1-FH1-FH2 dimer show the leading FH1 can better transfer profilin or profilin-actin, having decreasing probability with increasing distance from FH2
Brigitte M. Jockusch - One of the best experts on this subject based on the ideXlab platform.
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fine tuning of neuronal architecture requires two profilin isoforms
Proceedings of the National Academy of Sciences of the United States of America, 2010Co-Authors: Kristin Michaelsen, Martin Rothkegel, Brigitte M. Jockusch, Kai Murk, Marta Zagrebelsky, Anita Dreznjak, Martin KorteAbstract:Two profilin isoforms (PFN1 and PFN2a) are expressed in the mammalian brain. Although Profilins are essential for regulating actin dynamics in general, the specific role of these isoforms in neurons has remained elusive. We show that knockdown of the neuron-specific PFN2a results in a significant reduction in dendrite complexity and spine numbers of hippocampal neurons. Overexpression of PFN1 in PFN2a-deficient neurons prevents the loss of spines but does not restore dendritic complexity. Furthermore, we show that Profilins are involved in differentially regulating actin dynamics downstream of the pan-neurotrophin receptor (p75NTR), a receptor engaged in modulating neuronal morphology. Overexpression of PFN2a restores the morphological changes in dendrites caused by p75NTR overexpression, whereas PFN1 restores the normal spine density. Our data assign specific functions to the two PFN isoforms, possibly attributable to different affinities for potent effectors also involved in actin dynamics, and suggest that they are important for the signal-dependent fine-tuning of neuronal architecture.
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The profile of Profilins
Reviews of physiology biochemistry and pharmacology, 2007Co-Authors: Brigitte M. Jockusch, Kai Murk, Martin RothkegelAbstract:Profilins are small proteins involved in actin dynamics. In accordance with this function, they are found in all eukaryotes and are structurally highly conserved. However, their precise role in regulating actin-related functions is just beginning to emerge. This article recapitulates the wealth of information on structure, expression and functions accumulated on Profilins from many different organisms in the 30 years after their discovery as actin-binding proteins. Emphasis is given to their interaction with a plethora of many different ligands in the cytoplasm as well as in the nucleus, which is considered the basis for their various activities and the significance of the tissue-specific expression of profilin isoforms.
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a role for polyproline motifs in the spinal muscular atrophy protein smn Profilins bind to and colocalize with smn in nuclear gems
Journal of Biological Chemistry, 1999Co-Authors: Torsten Giesemann, Martin Rothkegel, Brigitte M. Jockusch, Silvia Rathkehartlieb, Jorg W Bartsch, Sabine Buchmeier, Harald JockuschAbstract:Next Section Abstract Spinal muscular atrophy (SMA) is an autosomal recessive disorder characterized by the loss of α-motoneurons in the spinal cord followed by atrophy of skeletal muscles. SMA-determining candidate genes, SMN1 and SMN2, have been identified on human chromosome 5q. The corresponding SMN protein is expressed ubiquitously. It is coded by seven exons and contains conspicuous proline-rich motifs in its COOH-terminal third (exons 4, 5, and 6). Such motifs are known to bind to Profilins (PFNs), small proteins engaged in the control of actin dynamics. We tested whether Profilins interact with SMN via its polyproline stretches. Using the yeast two-hybrid system we show that Profilins bind to SMN and that this binding depends on its proline-rich motifs. These results were confirmed by coimmunoprecipitation and by in vitro binding studies. Two PFN isoforms, I and II, are known, of which II is characteristic for central nervous system tissue. We show by in situ hybridization that both PFNs are highly expressed in mouse spinal cord and that PFN II is expressed predominantly in neurons. In motoneurons, the primary target of neurodegeneration in SMA, Profilins are highly concentrated and colocalize with SMN in the cytoplasm of the cell body and in nuclear gems. Likewise, SMN and PFN I colocalize in gems of HeLa cells. Although SMN interacts with both profilin isoforms, binding of PFN II was stronger than of PFN I in all assays employed. Because the SMN genes are expressed ubiquitously, our findings suggest that the interaction of PFN II with SMN may be involved in neuron-specific effects of SMN mutations.
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a role for polyproline motifs in the spinal muscular atrophy protein smn Profilins bind to and colocalize with smn in nuclear gems
Journal of Biological Chemistry, 1999Co-Authors: Torsten Giesemann, Martin Rothkegel, Brigitte M. Jockusch, Silvia Rathkehartlieb, Jorg W Bartsch, Sabine Buchmeier, Harald JockuschAbstract:Spinal muscular atrophy (SMA) is an autosomal recessive disorder characterized by the loss of α-motoneurons in the spinal cord followed by atrophy of skeletal muscles. SMA-determining candidate genes, SMN1 and SMN2, have been identified on human chromosome 5q. The corresponding SMN protein is expressed ubiquitously. It is coded by seven exons and contains conspicuous proline-rich motifs in its COOH-terminal third (exons 4, 5, and 6). Such motifs are known to bind to Profilins (PFNs), small proteins engaged in the control of actin dynamics. We tested whether Profilins interact with SMN via its polyproline stretches. Using the yeast two-hybrid system we show that Profilins bind to SMN and that this binding depends on its proline-rich motifs. These results were confirmed by coimmunoprecipitation and by in vitro binding studies. Two PFN isoforms, I and II, are known, of which II is characteristic for central nervous system tissue. We show by in situ hybridization that both PFNs are highly expressed in mouse spinal cord and that PFN II is expressed predominantly in neurons. In motoneurons, the primary target of neurodegeneration in SMA, Profilins are highly concentrated and colocalize with SMN in the cytoplasm of the cell body and in nuclear gems. Likewise, SMN and PFN I colocalize in gems of HeLa cells. Although SMN interacts with both profilin isoforms, binding of PFN II was stronger than of PFN I in all assays employed. Because the SMN genes are expressed ubiquitously, our findings suggest that the interaction of PFN II with SMN may be involved in neuron-specific effects of SMN mutations.
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Differential colocalization of profilin with microfilaments in PtK2 cells
Cell motility and the cytoskeleton, 1997Co-Authors: Oleg A. Mayboroda, Kathrin Schluter, Brigitte M. JockuschAbstract:Profilins are thought to be involved in the control of actin dynamics in eukaryotic cells. In accordance with this concept, profilin was found to be colocalized with the cortical microfilament webs in leading lamellae of locomoting and spreading fibroblasts. However, so far, there is little information on the distribution of profilin in other cell types. In this study, we report on the colocalization of profilin with various microfilament suprastructures in the epithelial cell line PtK2. This cell line, which is derived from rat kangaroo, contains a profilin sharing an N-terminal epitope with bovine and human profilin I, as seen by immunoblotting with monoclonal antibodies. By using immunofluorescence in conjunction with conventional fluorescence microscopy and confocal laser-scanning microscopy, we found profilin in ruffling areas of the peripheral lamellae and nascent stress fibers of spreading cells, whereas the peripheral belts of stationary cells growing in epithelioid sheets lacked profilin staining. In these cells, profilin was primarily distributed in a fine reticular or vesicular network that was not related to the microfilament system. Conspicuously low levels of Profilins was not related to the contractile ring of mitotic cells. This was found for different fixation protocols and antibodies of the IgG and IgM type, respectively, indicating that lack of staining of the cleavage furrow was not due to antibody penetration problems. Depending on the fixation protocol, the nuclear matrix appeared strongly positive or negative for profilin. Cells microinjected with birch pollen profilin and labeled with a birch profilin-specific monoclonal antibody corroborated the results obtained with the endogeneous protein: The injected profilin was targeted to the cortical web and to nascent stress fibers of spreading cells but not to the cleavage ring of mitotic cells. These results suggest that high concentrations of a profilin I homologue are preferentially located with those microfilament suprastructures in PtK2 cells that are subject to rapid modulation by external signals.
Brandon Gregory Horan - One of the best experts on this subject based on the ideXlab platform.
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computational modeling highlights the role of the disordered formin homology 1 domain in profilin actin transfer
FEBS Letters, 2018Co-Authors: Brandon Gregory Horan, Gül H Zerze, Dimitrios Vavylonis, Youngchan Kim, Jeetain MittalAbstract:Formins accelerate actin polymerization, assumed to occur through flexible Formin Homology 1 (FH1) domain-mediated transfer of profilin-actin to the barbed end. To study FH1 properties and address sequence effects, including varying length/distribution of profilin-binding proline-rich motifs, we performed all-atom simulations of a set of representative FH1 domains of formins: mouse mDia1 and mDia2, budding yeast Bni1 and Bnr1, and fission yeast Cdc12, For3, and Fus1. We find FH1 has flexible regions between high-propensity polyproline helix regions. A coarse-grained model retaining sequence specificity, assuming rigid polyproline segments, describes their size. Multiple bound Profilins or profilin-actin complexes expand mDia1-FH1, which may be important in cells. Simulations of the barbed end bound to Bni1-FH1-FH2 dimer show that the leading FH1 can better transfer profilin or profilin-actin, with decreasing probability as the distance from FH2 increases.
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computational modeling highlights disordered formin homology 1 domain s role in profilin actin transfer
bioRxiv, 2018Co-Authors: Brandon Gregory Horan, Gül H Zerze, Dimitrios Vavylonis, Youngchan Kim, Jeetain MittalAbstract:Formins accelerate actin polymerization, assumed to occur through flexible FH1 domain mediated transfer of profilin-actin to the barbed end. To study FH1 properties and address sequence effects including varying length/distribution of profilin-binding proline-rich motifs, we performed all-atom simulations of mouse mDia1, mDia2; budding yeast Bni1, Bnr1; fission yeast Cdc12, For3, and Fus1 FH1s. We find FH1 has flexible regions between high propensity polyproline helix regions. A coarse-grained model retaining sequence-specificity, assuming rigid polyproline segments, describes their size. Multiple Profilins and profilin-actin complexes can simultaneously bind, expanding mDia1-FH1, which may be important in cells. Simulations of the barbed end bound to Bni1-FH1-FH2 dimer show the leading FH1 can better transfer profilin or profilin-actin, having decreasing probability with increasing distance from FH2.
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Dataset for: Computational modeling highlights disordered Formin Homology 1 domain's role in profilin-actin transfer
2018Co-Authors: Brandon Gregory Horan, Gül H Zerze, Young C. Kim, Dimitrios Vavylonis, Jeetain MittalAbstract:Formins accelerate actin polymerization, assumed to occur through flexible FH1 domain mediated transfer of profilin-actin to the barbed end. To study FH1 properties and address sequence effects including varying length/distribution of profilin-binding proline-rich motifs, we performed all-atom simulations of mouse mDia1, mDia2; budding yeast Bni1, Bnr1; fission yeast Cdc12, For3, and Fus1 FH1s. We find FH1 has flexible regions between high propensity polyproline helix regions. A coarse-grained model retaining sequence-specificity, assuming rigid polyproline segments, describes their size. Multiple bound Profilins or profilin-actin complexes expand mDia1-FH1, which may be important in cells. Simulations of the barbed end bound to Bni1-FH1-FH2 dimer show the leading FH1 can better transfer profilin or profilin-actin, having decreasing probability with increasing distance from FH2
Harald Jockusch - One of the best experts on this subject based on the ideXlab platform.
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a role for polyproline motifs in the spinal muscular atrophy protein smn Profilins bind to and colocalize with smn in nuclear gems
Journal of Biological Chemistry, 1999Co-Authors: Torsten Giesemann, Martin Rothkegel, Brigitte M. Jockusch, Silvia Rathkehartlieb, Jorg W Bartsch, Sabine Buchmeier, Harald JockuschAbstract:Next Section Abstract Spinal muscular atrophy (SMA) is an autosomal recessive disorder characterized by the loss of α-motoneurons in the spinal cord followed by atrophy of skeletal muscles. SMA-determining candidate genes, SMN1 and SMN2, have been identified on human chromosome 5q. The corresponding SMN protein is expressed ubiquitously. It is coded by seven exons and contains conspicuous proline-rich motifs in its COOH-terminal third (exons 4, 5, and 6). Such motifs are known to bind to Profilins (PFNs), small proteins engaged in the control of actin dynamics. We tested whether Profilins interact with SMN via its polyproline stretches. Using the yeast two-hybrid system we show that Profilins bind to SMN and that this binding depends on its proline-rich motifs. These results were confirmed by coimmunoprecipitation and by in vitro binding studies. Two PFN isoforms, I and II, are known, of which II is characteristic for central nervous system tissue. We show by in situ hybridization that both PFNs are highly expressed in mouse spinal cord and that PFN II is expressed predominantly in neurons. In motoneurons, the primary target of neurodegeneration in SMA, Profilins are highly concentrated and colocalize with SMN in the cytoplasm of the cell body and in nuclear gems. Likewise, SMN and PFN I colocalize in gems of HeLa cells. Although SMN interacts with both profilin isoforms, binding of PFN II was stronger than of PFN I in all assays employed. Because the SMN genes are expressed ubiquitously, our findings suggest that the interaction of PFN II with SMN may be involved in neuron-specific effects of SMN mutations.
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a role for polyproline motifs in the spinal muscular atrophy protein smn Profilins bind to and colocalize with smn in nuclear gems
Journal of Biological Chemistry, 1999Co-Authors: Torsten Giesemann, Martin Rothkegel, Brigitte M. Jockusch, Silvia Rathkehartlieb, Jorg W Bartsch, Sabine Buchmeier, Harald JockuschAbstract:Spinal muscular atrophy (SMA) is an autosomal recessive disorder characterized by the loss of α-motoneurons in the spinal cord followed by atrophy of skeletal muscles. SMA-determining candidate genes, SMN1 and SMN2, have been identified on human chromosome 5q. The corresponding SMN protein is expressed ubiquitously. It is coded by seven exons and contains conspicuous proline-rich motifs in its COOH-terminal third (exons 4, 5, and 6). Such motifs are known to bind to Profilins (PFNs), small proteins engaged in the control of actin dynamics. We tested whether Profilins interact with SMN via its polyproline stretches. Using the yeast two-hybrid system we show that Profilins bind to SMN and that this binding depends on its proline-rich motifs. These results were confirmed by coimmunoprecipitation and by in vitro binding studies. Two PFN isoforms, I and II, are known, of which II is characteristic for central nervous system tissue. We show by in situ hybridization that both PFNs are highly expressed in mouse spinal cord and that PFN II is expressed predominantly in neurons. In motoneurons, the primary target of neurodegeneration in SMA, Profilins are highly concentrated and colocalize with SMN in the cytoplasm of the cell body and in nuclear gems. Likewise, SMN and PFN I colocalize in gems of HeLa cells. Although SMN interacts with both profilin isoforms, binding of PFN II was stronger than of PFN I in all assays employed. Because the SMN genes are expressed ubiquitously, our findings suggest that the interaction of PFN II with SMN may be involved in neuron-specific effects of SMN mutations.
Martin Rothkegel - One of the best experts on this subject based on the ideXlab platform.
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Illustration of the proposed cellular function of Profilins in glia-neuronal networks.
2015Co-Authors: Stefanie K. Schweinhuber, Martin Korte, Tania Meßerschmidt, Robert Hänsch, Martin RothkegelAbstract:(A) In the presence of all actin binding proteins, astrocytes are very complex and occupy large areas. Their highly motile processes (PAP) sense and modify synaptic input on the engulfed synapse. Profilins might regulate the motility of these processes either by direct binding to actin (PFN1) or by influencing its dynamics (PFN2a). (B) The absence of Profilins results in a reduced size and complexity of astrocytes. Motility of astrocytic processes deficient of profilin isoforms is drastically reduced. This may lead to altered synaptic properties and plasticity.
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Profilin Isoforms Modulate Astrocytic Morphology and the Motility of Astrocytic Processes
2015Co-Authors: Stefanie K. Schweinhuber, Martin Korte, Tania Meßerschmidt, Robert Hänsch, Martin RothkegelAbstract:The morphology of astrocytic processes determines their close structural association with synapses referred to as the ‘tripartite synapse’. Concerted morphological plasticity processes at tripartite synapses are supposed to shape neuronal communication. Morphological changes in astrocytes as well as the motility of astrocytic processes require remodeling of the actin cytoskeleton. Among the regulators of fast timescale actin-based motility, the actin binding protein profilin 1 has recently been shown to control the activity-dependent outgrowth of astrocytic processes.Here, we demonstrate that cultured murine astrocytes in addition to the ubiquitous profilin 1 also express the neuronal isoform profilin 2a. To analyze the cellular function of both Profilins in astrocytes, we took advantage of a shRNA mediated isoform-specific downregulation. Interestingly, consistent with earlier results in neurons, we found redundant as well as isoform-specific functions of both Profilins in modulating cellular physiology. The knockdown of either profilin 1 or profilin 2a led to a significant decrease in cell spreading of astrocytes. In contrast, solely the knockdown of profilin 2a resulted in a significantly reduced morphological complexity of astrocytes in both dissociated and slice culture astrocytes. Moreover, both isoforms proved to be crucial for forskolin-induced astrocytic stellation. Furthermore, forskolin treatment resulted in isoform-specific changes in the phosphorylation level of profilin 1 and profilin 2a, leading to a PKA-dependent phosphorylation of profilin 2a. In addition, transwell assays revealed an involvement of both isoforms in the motility of astrocytic processes, while FRAP analysis displayed an isoform-specific role of profilin 1 in the regulation of actin dynamics in peripheral astrocytic processes. Taken together, we suggest profilin isoforms to be important modulators of astrocytic morphology and motility with overlapping as well as isoform-specific functions.
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fine tuning of neuronal architecture requires two profilin isoforms
Proceedings of the National Academy of Sciences of the United States of America, 2010Co-Authors: Kristin Michaelsen, Martin Rothkegel, Brigitte M. Jockusch, Kai Murk, Marta Zagrebelsky, Anita Dreznjak, Martin KorteAbstract:Two profilin isoforms (PFN1 and PFN2a) are expressed in the mammalian brain. Although Profilins are essential for regulating actin dynamics in general, the specific role of these isoforms in neurons has remained elusive. We show that knockdown of the neuron-specific PFN2a results in a significant reduction in dendrite complexity and spine numbers of hippocampal neurons. Overexpression of PFN1 in PFN2a-deficient neurons prevents the loss of spines but does not restore dendritic complexity. Furthermore, we show that Profilins are involved in differentially regulating actin dynamics downstream of the pan-neurotrophin receptor (p75NTR), a receptor engaged in modulating neuronal morphology. Overexpression of PFN2a restores the morphological changes in dendrites caused by p75NTR overexpression, whereas PFN1 restores the normal spine density. Our data assign specific functions to the two PFN isoforms, possibly attributable to different affinities for potent effectors also involved in actin dynamics, and suggest that they are important for the signal-dependent fine-tuning of neuronal architecture.
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testis expressed Profilins 3 and 4 show distinct functional characteristics and localize in the acroplaxome manchette complex in spermatids
BMC Cell Biology, 2009Co-Authors: Martina Behnen, Petri Kursula, Martin Rothkegel, Kai Murk, Heike Cappalloobermann, Abraham L Kierszenbaum, Christiane KirchhoffAbstract:Multiple profilin isoforms exist in mammals; at least four are expressed in the mammalian testis. The testis-specific isoforms profilin-3 (PFN3) and profilin-4 (PFN4) may have specialized roles in spermatogenic cells which are distinct from known functions fulfilled by the "somatic" Profilins, profilin-1 (PFN1) and profilin-2 (PFN2). Ligand interactions and spatial distributions of PFN3 and PFN4 were compared by biochemical, molecular and immunological methods; PFN1 and PFN2 were employed as controls. β-actin, phosphoinositides, poly-L-proline and mDia3, but not VASP, were confirmed as in vitro interaction partners of PFN3. In parallel experiments, PFN4 bound to selected phosphoinositides but not to poly-L-proline, proline-rich proteins, or actin. Immunofluorescence microscopy of PFN3 and PFN4 revealed distinct subcellular locations in differentiating spermatids. Both were associated first with the acroplaxome and later with the transient manchette. Predicted 3D structures indicated that PFN3 has the actin-binding site conserved, but retains only approximately half of the common poly-L-proline binding site. PFN4, in comparison, has lost both, polyproline and actin binding sites completely, which is well in line with the experimental data. The testis-specific isoform PFN3 showed major hallmarks of the well characterized "somatic" profilin isoforms, albeit with distinct binding affinities. PFN4, on the other hand, did not interact with actin or polyproline in vitro. Rather, it seemed to be specialized for phospholipid binding, possibly providing cellular functions which are distinct from actin dynamics regulation.
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The profile of Profilins
Reviews of physiology biochemistry and pharmacology, 2007Co-Authors: Brigitte M. Jockusch, Kai Murk, Martin RothkegelAbstract:Profilins are small proteins involved in actin dynamics. In accordance with this function, they are found in all eukaryotes and are structurally highly conserved. However, their precise role in regulating actin-related functions is just beginning to emerge. This article recapitulates the wealth of information on structure, expression and functions accumulated on Profilins from many different organisms in the 30 years after their discovery as actin-binding proteins. Emphasis is given to their interaction with a plethora of many different ligands in the cytoplasm as well as in the nucleus, which is considered the basis for their various activities and the significance of the tissue-specific expression of profilin isoforms.
