Activation of RGS9-1GTPase Acceleration by Its Membrane Anchor, R9AP

Hu, Guang; Zhang, Zhixian; Wensel, Theodore G.

doi:10.1074/jbc.m212046200

Cited by 70 publications

(62 citation statements)

References 38 publications

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“…Our experimental approach replicated that used to establish the DEP domain as the R9AP interacting site (7,8). We used The interaction between recombinant GST-tagged R7BP and RGS9/ G␤5 constructs was analyzed in pull-down assays as described under "Experimental Procedures."…”

Section: R7bp Is Specifically Expressed In the Nervous System-mentioning

confidence: 99%

“…Finally, R9AP enhances the ability of RGS9-1 to stimulate G protein GTPase activity thus allowing the visual signal to be terminated on the physiologically rapid time scale (5,7,8). RGS9-1 interaction with R9AP is mediated by the N-terminal domain of RGS9-1 called DEP (7,8).The physiological significance of RGS9-1 interaction with R9AP was emphasized in a recent human study of patients bearing defects in either RGS9 or R9AP molecules (9). The mutations of either protein resulted in a clinical phenotype characterized by impaired ability to adjust to bright light and by impaired temporal resolution of the visual signals resulting in reduced ability to see moving objects.…”

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confidence: 99%

“…It also determines the RGS9-1 expression level by protecting RGS9-1 from proteolytic degradation in the cell (6). Finally, R9AP enhances the ability of RGS9-1 to stimulate G protein GTPase activity thus allowing the visual signal to be terminated on the physiologically rapid time scale (5,7,8). RGS9-1 interaction with R9AP is mediated by the N-terminal domain of RGS9-1 called DEP (7,8).…”

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confidence: 99%

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R7BP, a Novel Neuronal Protein Interacting with RGS Proteins of the R7 Family

Martemyanov

Yoo

Skiba

et al. 2005

Journal of Biological Chemistry

136

192

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The R7 subfamily of the regulators of G protein signaling (RGS) proteins is represented by four members broadly expressed in the mammalian nervous system. Here we report that in the brain all four R7 proteins form tight complexes with a previously unidentified protein, which we call the R7-binding protein or R7BP. We initially identified R7BP as a protein co-precipitating with the R7 protein, RGS9, from extracts obtained from the striatal region of the brain. We further showed that R7BP forms a tight complex with RGS9 in vitro and that this binding occurs via the N-terminal DEP domain of RGS9. R7BP is expressed throughout the entire central nervous system but not in any of the tested nonneuronal tissues. All four R7 RGS proteins co-precipitate with R7BP from brain extracts and recombinant R7 proteins bind recombinant R7BP with high efficiency. The closest homolog of R7BP is R9AP which was previously found to interact with RGS9 in photoreceptors. Both R7BP and R9AP are related to the syntaxin subfamily of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins involved in vesicular trafficking and exocytosis. In photoreceptors R9AP regulates several critical properties of RGS9 including its intracellular targeting, stability and catalytic activity. This suggests that R7BP interactions with R7 proteins in the brain may also bear major functional significance. RGS1 proteins regulate the duration of G protein signaling by stimulating the rate of the GTP hydrolysis on G protein ␣ subunits (reviewed in Refs. 1 and 2). RGS proteins are classified in six to nine subfamilies based on the homology within the RGS catalytic domain (1-3). Most RGS proteins contain additional noncatalytic domains that modulate the properties of their catalytic domains and allow them to interact with their partners in a broad range of signaling pathways. The R7 (also called "C") subfamily of RGS proteins contains four members expressed in the mammalian nervous system, RGS6, RGS7, RGS9, and RGS11 (reviewed in Ref. 4). R7 proteins share common domain composition and exist as constitutive complexes with the type 5 G protein ␤ subunit (G␤5).Marked progress in the understanding of the function of the R7 protein came from the studies of the short splice variant of RGS9, RGS9-1, which regulates signal duration in the phototransduction pathway in vertebrate rod and cone photoreceptors. Several functional properties of RGS9-1 in photoreceptors are regulated by its interacting partner, a SNARE-like protein R9AP. R9AP is responsible for targeting RGS9-1 to the photoreceptor outer segment, an intracellular compartment where phototransduction takes place (5). It also determines the RGS9-1 expression level by protecting RGS9-1 from proteolytic degradation in the cell (6). Finally, R9AP enhances the ability of RGS9-1 to stimulate G protein GTPase activity thus allowing the visual signal to be terminated on the physiologically rapid time scale (5,7,8). RGS9-1 interaction with R9AP is mediated by the N-terminal domain of RGS9-1 c...

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Section: R7bp Is Specifically Expressed In the Nervous System-mentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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R7BP, a Novel Neuronal Protein Interacting with RGS Proteins of the R7 Family

Martemyanov

Yoo

Skiba

et al. 2005

Journal of Biological Chemistry

136

192

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“…We next examined the expression of cone cascade modulator, R9AP, a protein that forms a tight complex with RGS9 and G␤5 (Hu et al, 2003;Martemyanov and Arshavsky, 2009). R9AP was concentrated in the cone outer segments (Fig.…”

Section: Absence Of G␤3 Does Not Affect Other Components Of the Cone mentioning

confidence: 99%

Cones Respond to Light in the Absence of Transducin β Subunit

Nikonov¹,

Lyubarsky

Fina³

et al. 2013

J. Neurosci.

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Mammalian cones respond to light by closing a cGMP-gated channel via a cascade that includes a heterotrimeric G-protein, cone transducin, comprising G␣t2, G␤3 and G␥t2 subunits. The function of G␤␥ in this cascade has not been examined. Here, we investigate the role of G␤3 by assessing cone structure and function in G␤3-null mouse (Gnb3 Ϫ/Ϫ ). We found that G␤3 is required for the normal expression of its partners, because in the Gnb3 Ϫ/Ϫ cone outer segments, the levels of G␣t2 and G␥t2 are reduced by fourfold to sixfold, whereas other components of the cascade remain unaltered. Surprisingly, Gnb3Ϫ/Ϫ cones produce stable responses with normal kinetics and saturating response amplitudes similar to that of the wild-type, suggesting that cone phototransduction can function efficiently without a G␤ subunit. However, light sensitivity was reduced by approximately fourfold in the knock-out cones. Because the reduction in sensitivity was similar in magnitude to the reduction in G␣t2 level in the cone outer segment, we conclude that activation of G␣t2 in Gnb3 Ϫ/Ϫ cones proceeds at a rate approximately proportional to its outer segment concentration, and that activation of phosphodiesterase and downstream cascade components is normal. These results suggest that the main role of G␤3 in cones is to establish optimal levels of transducin heteromer in the outer segment, thereby indirectly contributing to robust response properties.

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“…The activated G␣ t GTP/PDE6 complex is membrane bound and stabilized by the G␣ t and PDE6 lipid modifications (Catty et al, 1992;Clerc and Bennett, 1992). The ability of the GAP complex to rapidly inactivate the G␣ t GTP/PDE6 complex depends on the membrane attachment of the GAP complex via the anchor protein, R9AP (Lishko et al, 2002, Hu et al, 2003.…”

Section: Introductionmentioning

confidence: 99%

N-Terminal Fatty Acylation of Transducin Profoundly Influences Its Localization and the Kinetics of Photoresponse in Rods

Kerov¹,

Rubin²,

Natochin³

et al. 2007

J. Neurosci.

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N-terminal acylation of the ␣-subunits of heterotrimeric G-proteins is believed to play a major role in regulating the cellular localization and signaling of G-proteins, but physiological evidence has been lacking. To examine the functional significance of N-acylation of a well understood G-protein ␣-subunit, transducin (G␣ t ), we generated transgenic mice that expressed a mutant G␣ t lacking N-terminal acylation sequence (G␣ t G2A). Rods expressing G␣ t G2A showed a severe defect in transducin cellular localization. In contrast to native G␣ t , which resides in the outer segments of dark-adapted rods, G␣ t G2A was found predominantly in the inner compartments of the photoreceptor cells. Remarkably, transgenic rods with the outer segments containing G␣ t G2A at 5-6% of the G␣ t levels in wild-type rods showed only a sixfold reduction in sensitivity and a threefold decrease in the amplification constant. The much smaller than predicted reduction may reflect an increase in the lateral diffusion of transducin and an increased activation rate by photoexcited rhodopsin or more efficient activation of cGMP phosphodiesterase 6 by G␣ t G2A; alternatively, nonlinear relationships between concentration and the activation rate of transducin also potentially contribute to the mismatch between the amplification constant and quantitative expression analysis of G␣ t G2A rods. Furthermore, the G2A mutation reduced the GTPase activity of transducin and resulted in two to three times slower than normal recovery of flash responses of transgenic rods, indicating the role of G␣ t membrane tethering for its efficient inactivation by the regulator of G-protein signaling 9 GTPase-activating protein complex. Thus, N-acylation is critical for correct compartmentalization of transducin and controls the rate of its deactivation.

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Activation of RGS9-1GTPase Acceleration by Its Membrane Anchor, R9AP

Cited by 70 publications

References 38 publications

R7BP, a Novel Neuronal Protein Interacting with RGS Proteins of the R7 Family

R7BP, a Novel Neuronal Protein Interacting with RGS Proteins of the R7 Family

Cones Respond to Light in the Absence of Transducin β Subunit

N-Terminal Fatty Acylation of Transducin Profoundly Influences Its Localization and the Kinetics of Photoresponse in Rods

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