The Experts below are selected from a list of 144 Experts worldwide ranked by ideXlab platform
T. Kendall Harden - One of the best experts on this subject based on the ideXlab platform.
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Crystal structure of the multifunctional Gβ5–RGS9 complex
Nature Structural & Molecular Biology, 2008Co-Authors: Matthew L Cheever, T. Kendall Harden, David P. Siderovski, Jason T Snyder, Svetlana Gershburg, John SondekAbstract:Regulators of G-protein signaling (RGS) proteins enhance the intrinsic GTPase activity of G protein α (Gα) subunits and are vital for proper signaling kinetics downstream of G protein–coupled receptors (GPCRs). R7 subfamily RGS proteins specifically and obligately dimerize with the atypical G protein β5 (Gβ5) subunit through an internal G protein γ (Gγ)-subunit–like (GGL) Domain. Here we present the 1.95-Å crystal structure of the Gβ5–RGS9 complex, which is essential for normal visual and neuronal signal transduction. This structure reveals a canonical RGS Domain that is functionally integrated within a molecular complex that is poised for integration of multiple steps during G-protein activation and deactivation.
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RGS6, RGS7, RGS9, and RGS11 stimulate GTPase activity of Gifamily G-proteins with differential selectivity and maximal activity
The Journal of biological chemistry, 2003Co-Authors: Shelley B. Hooks, Andrejs M Krumins, G L Waldo, James Corbitt, Erik T. Bodor, T. Kendall HardenAbstract:Abstract Regulator of G-protein signaling (RGS) proteins are GTPase activating proteins (GAPs) of heterotrimeric G-proteins that alter the amplitude and kinetics of receptor-promoted signaling. In this study we defined the G-protein α-subunit selectivity of purified Sf9 cell-derived R7 proteins, a subfamily of RGS proteins (RGS6, -7, -9, and -11) containing a Gγ-like (GGL) Domain that mediates dimeric interaction with Gβ5. Gβ5/R7 dimers stimulated steady state GTPase activity of Gα-subunits of the Gi family, but not of Gαq or Gα11, when added to proteoliposomes containing M2 or M1 muscarinic receptor-coupled G-protein heterotrimers. Concentration effect curves of the Gβ5/R7 proteins revealed differences in potencies and efficacies toward Gα-subunits of the Gi family. Although all four Gβ5/R7 proteins exhibited similar potencies toward Gαo, Gβ5/RGS9 and Gβ5/RGS11 were more potent GAPs of Gαi1, Gαi2, and Gαi3 than were Gβ5/RGS6 and Gβ5/RGS7. The maximal GAP activity exhibited by Gβ5/RGS11 was 2- to 4-fold higher than that of Gβ5/RGS7 and Gβ5/RGS9, with Gβ5/RGS6 exhibiting an intermediate maximal GAP activity. Moreover, the less efficacious Gβ5/RGS7 and Gβ5/RGS9 inhibited Gβ5/RGS11-stimulated GTPase activity of Gαo. Therefore, R7 family RGS proteins are Gi family-selective GAPs with potentially important differences in activities.
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RGS6, RGS7, RGS9, and RGS11 stimulate GTPase activity of Gi family G-proteins with differential selectivity and maximal activity.
The Journal of biological chemistry, 2003Co-Authors: Shelley B. Hooks, Andrejs M Krumins, G L Waldo, James Corbitt, Erik T. Bodor, T. Kendall HardenAbstract:Abstract Regulator of G-protein signaling (RGS) proteins are GTPase activating proteins (GAPs) of heterotrimeric G-proteins that alter the amplitude and kinetics of receptor-promoted signaling. In this study we defined the G-protein α-subunit selectivity of purified Sf9 cell-derived R7 proteins, a subfamily of RGS proteins (RGS6, -7, -9, and -11) containing a Gγ-like (GGL) Domain that mediates dimeric interaction with Gβ5. Gβ5/R7 dimers stimulated steady state GTPase activity of Gα-subunits of the Gi family, but not of Gαq or Gα11, when added to proteoliposomes containing M2 or M1 muscarinic receptor-coupled G-protein heterotrimers. Concentration effect curves of the Gβ5/R7 proteins revealed differences in potencies and efficacies toward Gα-subunits of the Gi family. Although all four Gβ5/R7 proteins exhibited similar potencies toward Gαo, Gβ5/RGS9 and Gβ5/RGS11 were more potent GAPs of Gαi1, Gαi2, and Gαi3 than were Gβ5/RGS6 and Gβ5/RGS7. The maximal GAP activity exhibited by Gβ5/RGS11 was 2- to 4-fold higher than that of Gβ5/RGS7 and Gβ5/RGS9, with Gβ5/RGS6 exhibiting an intermediate maximal GAP activity. Moreover, the less efficacious Gβ5/RGS7 and Gβ5/RGS9 inhibited Gβ5/RGS11-stimulated GTPase activity of Gαo. Therefore, R7 family RGS proteins are Gi family-selective GAPs with potentially important differences in activities.
Rory A. Fisher - One of the best experts on this subject based on the ideXlab platform.
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RGS6 interacts with DMAP1 and DNMT1 and inhibits DMAP1 transcriptional repressor activity.
The Journal of biological chemistry, 2004Co-Authors: Zhengyu Liu, Rory A. FisherAbstract:Abstract RGS6 is a member of a subfamily of mammalian RGS proteins that possess DEP (disheveled, Egl-10, pleckstrin) and GGL (G protein γ subunit-like) Domains in addition to the hallmark RGS Domain. RGS proteins negatively regulate heterotrimeric G protein signaling by virtue of the GTPase-activating protein activity of their RGS Domains. RGS6 exists in multiple splice forms with a long (6L) or short (6S) N terminus, a complete or incomplete GGL Domain, in combination with various C-terminal Domains. Green fluorescent protein-tagged RGS6L and RGS6S forms exhibit predominantly cytoplasmic and nuclear patterns of distribution in COS-7 cells, respectively, and traffic from these sites to nucleoli in response to stress signaling. We undertook a yeast two-hybrid screen for nuclear RGS6-binding proteins and here identify DMAP1 as an RGS6-interacting protein. DMAP1 is a component of the Dnmt1 complex involved in repression of newly replicated genes. The Domains of interaction were mapped to the N-terminal region of the GGL Domain of RGS6, a region distinct from its Gβ5 binding region, and the C-terminal Domain of DMAP1. Gβ5 and DMAP1 did not compete for each other's interaction with RGS6. Co-immunoprecipitation studies in COS-7 cells showed that RGS6L and RGS6S, but not RGS6LΔ258-293 deletion mutant lacking a DMAP1-binding module, co-immunoprecipitate DMAP1 as well as Dnmt1 in a DMAP1-dependent manner. A recombinant GGL Domain of RGS6 precipitated endogenous DMAP1 and Dnmt1 in neuroblastoma cell lysates and endogenous DMAP1 co-immunoprecipitated with RGS6L from mouse brain. Co-expression of DMAP1 with RGS6L promoted nuclear migration of RGS6L and its co-localization with DMAP1, a response not observed with RGS6LΔ258-293. RGS6 inhibited the transcriptional repressor activity of DMAP1. RGS6 is the first member of the RGS protein family shown to interact with proteins involved in transcriptional regulation.
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human rgs6 gene structure complex alternative splicing and role of n terminus and g protein γ subunit like GGL Domain in subcellular localization of rgs6 splice variants
Journal of Biological Chemistry, 2003Co-Authors: Tapan K. Chatterjee, Zhengyu Liu, Rory A. FisherAbstract:Abstract RGS proteins are defined by the presence of a semiconserved RGS Domain that confers the GTPase-activating activity of these proteins toward certain Gα subunits. RGS6 is a member of a subfamily of RGS proteins distinguished by the presence of DEP and GGL Domains, the latter a Gβ5-interacting Domain. Here we report identification of 36 distinct transcripts of human RGS6 that arise by unusually complex processing of the RGS6 gene, which spans 630 kilobase pairs of genomic DNA in human chromosome 14 and is interrupted by 19 introns. These transcripts arise by use of two alternative transcription sites and complex alternative splicing mechanisms and encode proteins with long or short N-terminal Domains, complete or incomplete GGL Domains, 7 distinct C-terminal Domains and a common internal Domain where the RGS Domain is found. The role of structural diversity in the N-terminal and GGL Domains of RGS6 splice variants in their interaction with Gβ5 and subcellular localization and of Gβ5 on RGS6 protein localization was examined in COS-7 cells expressing various RGS6 splice variant proteins. RGS6 splice variants with complete GGL Domains interacted with Gβ5, irrespective of the type of N-terminal Domain, while those lacking a complete GGL Domain did not. RGS6 protein variants displayed subcellular distribution patterns ranging from an exclusive cytoplasmic to exclusive nuclear/nucleolar localization, and co-expression of Gβ5 promoted nuclear localization of RGS6 proteins. Analysis of our results show that the long N-terminal and GGL Domain sequences of RGS6 proteins function as cytoplasmic retention sequences to prevent their nuclear/nucleolar accumulation. These findings provide the first evidence for Gβ5-independent functions of the GGL Domain and for a role of Gβ5 in RGS protein localization. This study reveals extraordinary complexity in processing of the human RGS6 gene and provides new insights into how structural diversity in the RGS6 protein family is involved in their localization and likely function(s) in cells.
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The human RGS6 protein family: Gene structure, complex alternative splicing and role of N-terminus and G-gamma subunit-like (GGL) Domain in subcellular localization of RGS6 splice variants
The Journal of biological chemistry, 2003Co-Authors: Tapan K. Chatterjee, Zhengyu Liu, Rory A. FisherAbstract:Abstract RGS proteins are defined by the presence of a semiconserved RGS Domain that confers the GTPase-activating activity of these proteins toward certain Gα subunits. RGS6 is a member of a subfamily of RGS proteins distinguished by the presence of DEP and GGL Domains, the latter a Gβ5-interacting Domain. Here we report identification of 36 distinct transcripts of human RGS6 that arise by unusually complex processing of the RGS6 gene, which spans 630 kilobase pairs of genomic DNA in human chromosome 14 and is interrupted by 19 introns. These transcripts arise by use of two alternative transcription sites and complex alternative splicing mechanisms and encode proteins with long or short N-terminal Domains, complete or incomplete GGL Domains, 7 distinct C-terminal Domains and a common internal Domain where the RGS Domain is found. The role of structural diversity in the N-terminal and GGL Domains of RGS6 splice variants in their interaction with Gβ5 and subcellular localization and of Gβ5 on RGS6 protein localization was examined in COS-7 cells expressing various RGS6 splice variant proteins. RGS6 splice variants with complete GGL Domains interacted with Gβ5, irrespective of the type of N-terminal Domain, while those lacking a complete GGL Domain did not. RGS6 protein variants displayed subcellular distribution patterns ranging from an exclusive cytoplasmic to exclusive nuclear/nucleolar localization, and co-expression of Gβ5 promoted nuclear localization of RGS6 proteins. Analysis of our results show that the long N-terminal and GGL Domain sequences of RGS6 proteins function as cytoplasmic retention sequences to prevent their nuclear/nucleolar accumulation. These findings provide the first evidence for Gβ5-independent functions of the GGL Domain and for a role of Gβ5 in RGS protein localization. This study reveals extraordinary complexity in processing of the human RGS6 gene and provides new insights into how structural diversity in the RGS6 protein family is involved in their localization and likely function(s) in cells.
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RGS6 Interacts with SCG10 and Promotes Neuronal Differentiation ROLE OF THE G GAMMA SUBUNIT-LIKE (GGL) Domain OF RGS6
The Journal of biological chemistry, 2002Co-Authors: Zhengyu Liu, Tapan K. Chatterjee, Rory A. FisherAbstract:RGS proteins comprise a large family of proteins named for their ability to negatively regulate heterotrimeric G protein signaling. RGS6 is a member of the R7 RGS protein subfamily endowed with DEP (disheveled, Egl-10, pleckstrin) and GGL (G protein gamma subunit-like) Domains in addition to the RGS Domain present in all RGS proteins. RGS6 exists in multiple splice variant forms with identical RGS Domains but possessing complete or incomplete GGL Domains and distinct N- and C-terminal Domains. Here we report that RGS6 interacts with SCG10, a neuronal growth-associated protein. Using yeast two-hybrid analysis to map protein interaction Domains, we identified the GGL Domain of RGS6 as the SCG10-interacting region and the stathmin Domain of SCG10 as the RGS6-interacting region. Pull-down studies in COS-7 cells expressing SCG10 and RGS6 splice variants revealed that SCG10 co-precipitated RGS6 proteins with complete GGL Domains but not those with incomplete GGL Domains, and vice versa. Expression of SCG10-interacting forms of RGS6 with SCG10 in PC12 or COS-7 cells resulted in co-localization of both proteins. RGS6 potentiated the ability of SCG10 to disrupt microtubule organization in PC12 and COS-7 cells. Furthermore, expression of SCG10 and RGS6 each enhanced NGF-induced PC12 cell differentiation, and co-expression of SCG10 with RGS6 produced synergistic effects on NGF-induced PC12 differentiation. These effects of RGS6 on microtubules and neuronal differentiation were observed only with RGS6 proteins with complete GGL Domains. Mutation of a critical residue required for interaction of RGS proteins with G proteins did not affect the ability of RGS6 to induce neuronal differentiation. These findings identify SCG10 as a binding partner for the GGL Domain of RGS6 and provide the first evidence for regulatory effects of an RGS protein on neuronal differentiation. Our results suggest that RGS6 induces neuronal differentiation by a novel mechanism involving interaction of SCG10 with its GGL Domain and independent of RGS6 interactions with heterotrimeric G proteins.
Andrejs M Krumins - One of the best experts on this subject based on the ideXlab platform.
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RGS6, RGS7, RGS9, and RGS11 stimulate GTPase activity of Gifamily G-proteins with differential selectivity and maximal activity
The Journal of biological chemistry, 2003Co-Authors: Shelley B. Hooks, Andrejs M Krumins, G L Waldo, James Corbitt, Erik T. Bodor, T. Kendall HardenAbstract:Abstract Regulator of G-protein signaling (RGS) proteins are GTPase activating proteins (GAPs) of heterotrimeric G-proteins that alter the amplitude and kinetics of receptor-promoted signaling. In this study we defined the G-protein α-subunit selectivity of purified Sf9 cell-derived R7 proteins, a subfamily of RGS proteins (RGS6, -7, -9, and -11) containing a Gγ-like (GGL) Domain that mediates dimeric interaction with Gβ5. Gβ5/R7 dimers stimulated steady state GTPase activity of Gα-subunits of the Gi family, but not of Gαq or Gα11, when added to proteoliposomes containing M2 or M1 muscarinic receptor-coupled G-protein heterotrimers. Concentration effect curves of the Gβ5/R7 proteins revealed differences in potencies and efficacies toward Gα-subunits of the Gi family. Although all four Gβ5/R7 proteins exhibited similar potencies toward Gαo, Gβ5/RGS9 and Gβ5/RGS11 were more potent GAPs of Gαi1, Gαi2, and Gαi3 than were Gβ5/RGS6 and Gβ5/RGS7. The maximal GAP activity exhibited by Gβ5/RGS11 was 2- to 4-fold higher than that of Gβ5/RGS7 and Gβ5/RGS9, with Gβ5/RGS6 exhibiting an intermediate maximal GAP activity. Moreover, the less efficacious Gβ5/RGS7 and Gβ5/RGS9 inhibited Gβ5/RGS11-stimulated GTPase activity of Gαo. Therefore, R7 family RGS proteins are Gi family-selective GAPs with potentially important differences in activities.
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RGS6, RGS7, RGS9, and RGS11 stimulate GTPase activity of Gi family G-proteins with differential selectivity and maximal activity.
The Journal of biological chemistry, 2003Co-Authors: Shelley B. Hooks, Andrejs M Krumins, G L Waldo, James Corbitt, Erik T. Bodor, T. Kendall HardenAbstract:Abstract Regulator of G-protein signaling (RGS) proteins are GTPase activating proteins (GAPs) of heterotrimeric G-proteins that alter the amplitude and kinetics of receptor-promoted signaling. In this study we defined the G-protein α-subunit selectivity of purified Sf9 cell-derived R7 proteins, a subfamily of RGS proteins (RGS6, -7, -9, and -11) containing a Gγ-like (GGL) Domain that mediates dimeric interaction with Gβ5. Gβ5/R7 dimers stimulated steady state GTPase activity of Gα-subunits of the Gi family, but not of Gαq or Gα11, when added to proteoliposomes containing M2 or M1 muscarinic receptor-coupled G-protein heterotrimers. Concentration effect curves of the Gβ5/R7 proteins revealed differences in potencies and efficacies toward Gα-subunits of the Gi family. Although all four Gβ5/R7 proteins exhibited similar potencies toward Gαo, Gβ5/RGS9 and Gβ5/RGS11 were more potent GAPs of Gαi1, Gαi2, and Gαi3 than were Gβ5/RGS6 and Gβ5/RGS7. The maximal GAP activity exhibited by Gβ5/RGS11 was 2- to 4-fold higher than that of Gβ5/RGS7 and Gβ5/RGS9, with Gβ5/RGS6 exhibiting an intermediate maximal GAP activity. Moreover, the less efficacious Gβ5/RGS7 and Gβ5/RGS9 inhibited Gβ5/RGS11-stimulated GTPase activity of Gαo. Therefore, R7 family RGS proteins are Gi family-selective GAPs with potentially important differences in activities.
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A G protein γ subunit-like Domain shared between RGS11 and other RGS proteins specifies binding to Gβ5 subunits
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Bryan E. Snow, Andrejs M Krumins, Sheu Fen Lee, Mark A. Wall, Stephen Chung, Joan Mangion, Sudha Arya, Alfred G GilmanAbstract:Regulators of G protein signaling (RGS) proteins act as GTPase-activating proteins (GAPs) toward the α subunits of heterotrimeric, signal-transducing G proteins. RGS11 contains a G protein γ subunit-like (GGL) Domain between its Dishevelled/Egl-10/Pleckstrin and RGS Domains. GGL Domains are also found in RGS6, RGS7, RGS9, and the Caenorhabditis elegans protein EGL-10. Coexpression of RGS11 with different Gβ subunits reveals specific interaction between RGS11 and Gβ5. The expression of mRNA for RGS11 and Gβ5 in human tissues overlaps. The Gβ5/RGS11 heterodimer acts as a GAP on Gαo, apparently selectively. RGS proteins that contain GGL Domains appear to act as GAPs for Gα proteins and form complexes with specific Gβ subunits, adding to the combinatorial complexity of G protein-mediated signaling pathways.
Shelley B. Hooks - One of the best experts on this subject based on the ideXlab platform.
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The G betagamma dimer as a novel source of selectivity in G-protein signaling: GGL-ing at convention.
Molecular interventions, 2004Co-Authors: Miller B. Jones, David P. Siderovski, Shelley B. HooksAbstract:Heterotrimeric G proteins relay information between cell surface receptors and effector molecules in diverse signaling pathways to mediate critical cellular processes in both physiologic and pathologic conditions. Multiple isoforms of each of the three G protein subunits yield enormous structural and functional diversity. G proteins are thus obvious molecular targets for the therapeutic manipulation of signaling pathways. Their ubiquity among a vast array of G protein-coupled receptor pathways, however, may at first seem to threaten the attractiveness of G proteins as drug targets for specific signaling processes; in order for G proteins to be effective targets, some degree of selectivity must be defined and exploited. Although a great deal has been determined about the functional selectivity of G alpha subunits, relatively little is known regarding G betagamma selectivity. In this review, we discuss functional diversity among G betagamma subunits in both receptor coupling and effector activation. The novel functions of G beta(5), in complex with proteins of the GGL Domain-containing R7 subfamily of regulators of G protein signaling, are discussed in detail, with specific focus on the potential of the G beta(5)-RGS9-2 pair as a therapeutic target in Parkinson's disease.
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RGS6, RGS7, RGS9, and RGS11 stimulate GTPase activity of Gifamily G-proteins with differential selectivity and maximal activity
The Journal of biological chemistry, 2003Co-Authors: Shelley B. Hooks, Andrejs M Krumins, G L Waldo, James Corbitt, Erik T. Bodor, T. Kendall HardenAbstract:Abstract Regulator of G-protein signaling (RGS) proteins are GTPase activating proteins (GAPs) of heterotrimeric G-proteins that alter the amplitude and kinetics of receptor-promoted signaling. In this study we defined the G-protein α-subunit selectivity of purified Sf9 cell-derived R7 proteins, a subfamily of RGS proteins (RGS6, -7, -9, and -11) containing a Gγ-like (GGL) Domain that mediates dimeric interaction with Gβ5. Gβ5/R7 dimers stimulated steady state GTPase activity of Gα-subunits of the Gi family, but not of Gαq or Gα11, when added to proteoliposomes containing M2 or M1 muscarinic receptor-coupled G-protein heterotrimers. Concentration effect curves of the Gβ5/R7 proteins revealed differences in potencies and efficacies toward Gα-subunits of the Gi family. Although all four Gβ5/R7 proteins exhibited similar potencies toward Gαo, Gβ5/RGS9 and Gβ5/RGS11 were more potent GAPs of Gαi1, Gαi2, and Gαi3 than were Gβ5/RGS6 and Gβ5/RGS7. The maximal GAP activity exhibited by Gβ5/RGS11 was 2- to 4-fold higher than that of Gβ5/RGS7 and Gβ5/RGS9, with Gβ5/RGS6 exhibiting an intermediate maximal GAP activity. Moreover, the less efficacious Gβ5/RGS7 and Gβ5/RGS9 inhibited Gβ5/RGS11-stimulated GTPase activity of Gαo. Therefore, R7 family RGS proteins are Gi family-selective GAPs with potentially important differences in activities.
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RGS6, RGS7, RGS9, and RGS11 stimulate GTPase activity of Gi family G-proteins with differential selectivity and maximal activity.
The Journal of biological chemistry, 2003Co-Authors: Shelley B. Hooks, Andrejs M Krumins, G L Waldo, James Corbitt, Erik T. Bodor, T. Kendall HardenAbstract:Abstract Regulator of G-protein signaling (RGS) proteins are GTPase activating proteins (GAPs) of heterotrimeric G-proteins that alter the amplitude and kinetics of receptor-promoted signaling. In this study we defined the G-protein α-subunit selectivity of purified Sf9 cell-derived R7 proteins, a subfamily of RGS proteins (RGS6, -7, -9, and -11) containing a Gγ-like (GGL) Domain that mediates dimeric interaction with Gβ5. Gβ5/R7 dimers stimulated steady state GTPase activity of Gα-subunits of the Gi family, but not of Gαq or Gα11, when added to proteoliposomes containing M2 or M1 muscarinic receptor-coupled G-protein heterotrimers. Concentration effect curves of the Gβ5/R7 proteins revealed differences in potencies and efficacies toward Gα-subunits of the Gi family. Although all four Gβ5/R7 proteins exhibited similar potencies toward Gαo, Gβ5/RGS9 and Gβ5/RGS11 were more potent GAPs of Gαi1, Gαi2, and Gαi3 than were Gβ5/RGS6 and Gβ5/RGS7. The maximal GAP activity exhibited by Gβ5/RGS11 was 2- to 4-fold higher than that of Gβ5/RGS7 and Gβ5/RGS9, with Gβ5/RGS6 exhibiting an intermediate maximal GAP activity. Moreover, the less efficacious Gβ5/RGS7 and Gβ5/RGS9 inhibited Gβ5/RGS11-stimulated GTPase activity of Gαo. Therefore, R7 family RGS proteins are Gi family-selective GAPs with potentially important differences in activities.
David P. Siderovski - One of the best experts on this subject based on the ideXlab platform.
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Selective Regulation of N-Type Ca Channels by Different Combinations of G-Protein �/ � Subunits and RGS Proteins
2013Co-Authors: Janice Y. Zhou, David P. Siderovski, Richard J. MillerAbstract:We examined the effects of G-protein � and � subunit heterodimers on human � 1B (N-type) Ca channels expressed in HEK293 cells. All of the known � subunits (�1–�5) produced voltage-dependent inhibition of � 1B Ca channels, depending on the � subunit found in the heterodimer. �1–�4 subunits inhibited Ca channels when paired with �1–�3. However, �5 subunits only produced inhibition when paired with �2. In contrast, heterodimers between �5 subunits and RGS (regulators of G-protein signaling) proteins containing GGL Domains did not produce inhibition of Ca channels. However, GGL Domain-containing RGS proteins (e.g., RGS6 and RGS11) did block the ability of G�5/�2 heterodimers to inhibit Ca channels. Because all of the G-protein � subunits are found in the nervous system, we conclude that they may all potentially participate in Ca channel inhibition. The interaction of GGL-containing RGS proteins with G�5�2 suggests a novel way in which Ca channels can be regulated. Key words: heterotrimeric G-proteins; calcium channel; ion– channel modulation; RGS proteins; presynaptic inhibition; synaptic transmission Activation of G-protein-coupled receptors (GPCRs) by neurotransmitters has been shown to induce the inhibition of several types of voltage-sensitive Ca channels, including �1B (N-type), �1A (P/Q-type), and �1E (R-type) (Miller, 1998; Simen and Miller, 1998, 2000). The resulting reduction in Ca influx may be important for GPCR-mediated inhibition of neurotransmitter release (Miller, 1998). Investigations of the mechanisms underlying GPCR-mediated Ca channel inhibition have shown that different processes can occur. The best studied of these is rapid and is characterized by its voltage dependence (Hille, 1994; Miller, 1998). The view is widely held that Ca channel inhibition of this type is mediated by the direct binding of G-protein �/ � subunits to one o
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Crystal structure of the multifunctional Gβ5–RGS9 complex
Nature Structural & Molecular Biology, 2008Co-Authors: Matthew L Cheever, T. Kendall Harden, David P. Siderovski, Jason T Snyder, Svetlana Gershburg, John SondekAbstract:Regulators of G-protein signaling (RGS) proteins enhance the intrinsic GTPase activity of G protein α (Gα) subunits and are vital for proper signaling kinetics downstream of G protein–coupled receptors (GPCRs). R7 subfamily RGS proteins specifically and obligately dimerize with the atypical G protein β5 (Gβ5) subunit through an internal G protein γ (Gγ)-subunit–like (GGL) Domain. Here we present the 1.95-Å crystal structure of the Gβ5–RGS9 complex, which is essential for normal visual and neuronal signal transduction. This structure reveals a canonical RGS Domain that is functionally integrated within a molecular complex that is poised for integration of multiple steps during G-protein activation and deactivation.
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The G betagamma dimer as a novel source of selectivity in G-protein signaling: GGL-ing at convention.
Molecular interventions, 2004Co-Authors: Miller B. Jones, David P. Siderovski, Shelley B. HooksAbstract:Heterotrimeric G proteins relay information between cell surface receptors and effector molecules in diverse signaling pathways to mediate critical cellular processes in both physiologic and pathologic conditions. Multiple isoforms of each of the three G protein subunits yield enormous structural and functional diversity. G proteins are thus obvious molecular targets for the therapeutic manipulation of signaling pathways. Their ubiquity among a vast array of G protein-coupled receptor pathways, however, may at first seem to threaten the attractiveness of G proteins as drug targets for specific signaling processes; in order for G proteins to be effective targets, some degree of selectivity must be defined and exploited. Although a great deal has been determined about the functional selectivity of G alpha subunits, relatively little is known regarding G betagamma selectivity. In this review, we discuss functional diversity among G betagamma subunits in both receptor coupling and effector activation. The novel functions of G beta(5), in complex with proteins of the GGL Domain-containing R7 subfamily of regulators of G protein signaling, are discussed in detail, with specific focus on the potential of the G beta(5)-RGS9-2 pair as a therapeutic target in Parkinson's disease.
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Gγ-like (GGL) Domains: New frontiers in G-protein signaling and β-propeller scaffolding
Biochemical pharmacology, 2001Co-Authors: John Sondek, David P. SiderovskiAbstract:The standard model of signal transduction from G-protein-coupled receptors (GPCRs) involves guanine nucleotide cycling by a heterotrimeric G-protein assembly composed of Galpha, Gbeta, and Ggamma subunits. The WD-repeat beta-propeller protein Gbeta and the alpha-helical, isoprenylated polypeptide Ggamma are considered obligate dimerization partners; moreover, conventional Gbetagamma heterodimers are considered essential to the functional coupling of Galpha subunits to receptors. However, our recent discovery of a Gbeta5 binding site (the Ggamma-like or "GGL" Domain) within several regulators of G-protein signaling (RGS) proteins revealed the potential for functional GPCR/Galpha coupling in the absence of a conventional Ggamma subunit. In addition, we posit that the interaction between Gbeta5 isoforms and the GGL Domains of RGS proteins represents a general mode of binding between beta-propeller proteins and their partners, extending beyond the realm of G-protein-linked signal transduction.
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Selective Regulation of N-Type Ca Channels by Different Combinations of G-Protein β/γ Subunits and RGS Proteins
The Journal of neuroscience : the official journal of the Society for Neuroscience, 2000Co-Authors: Janice Y. Zhou, David P. Siderovski, Richard J. MillerAbstract:We examined the effects of G-protein beta and gamma subunit heterodimers on human alpha(1B) (N-type) Ca channels expressed in HEK293 cells. All of the known beta subunits (beta1-beta5) produced voltage-dependent inhibition of alpha(1B) Ca channels, depending on the gamma subunit found in the heterodimer. beta1-beta4 subunits inhibited Ca channels when paired with gamma1-gamma3. However, beta5 subunits only produced inhibition when paired with gamma2. In contrast, heterodimers between beta5 subunits and RGS (regulators of G-protein signaling) proteins containing GGL Domains did not produce inhibition of Ca channels. However, GGL Domain-containing RGS proteins (e.g., RGS6 and RGS11) did block the ability of Gbeta5/gamma2 heterodimers to inhibit Ca channels. Because all of the G-protein beta subunits are found in the nervous system, we conclude that they may all potentially participate in Ca channel inhibition. The interaction of GGL-containing RGS proteins with Gbeta5gamma2 suggests a novel way in which Ca channels can be regulated.