Disease relevance of RGS19

• In the present study we show that the GAIP mRNA content declines during the enterocytic differentiation of two cell lines derived from human colon adenocarcinomas: HT-29 and Caco-2 [1].
• In undifferentiated HT-29 cells, when the GDP/GTP cycle on the trimeric Gi3 protein is interrupted by either pertussis toxin treatment or by the transfection of a mutant of the Galphai3 protein with no GTPase activity (Q204L), we observed a decrease in the GAIP mRNA content [1].
• Activation of ERK1/2 stimulates macroautophagy in the human colon cancer cell line HT-29 by favoring the phosphorylation of the Galpha-interacting protein (GAIP) in an amino acid-dependent manner (Ogier-Denis, E., Pattingre, S., El Benna, J., and Codogno, P. (2000) J. Biol. Chem. 275, 39090-39095) [2].
• Here we report the cloning and functional characterization of a unique cDNA isoform of GAIP, derived from embryonic chicken dorsal root ganglion neurons [3].

High impact information on RGS19

• GAIP and RGS4 are GTPase-activating proteins for the Gi subfamily of G protein alpha subunits [4].
• The extent of inhibition of Gz GAP, GAIP, RGS4, and RGS10 correlated roughly with their intrinsic GAP activities for the Galpha target used in the assay [5].
• GIPN (GAIP interacting protein N terminus) is a 38-kDa protein with an N-terminal leucine-rich region, a central RING finger-like domain, and a putative C-terminal transmembrane domain [6].
• Phosphoamino acid analysis revealed that phosphorylation of GAIP occurred largely on serine residues [7].
• Membrane-associated GAIP is a phosphoprotein and can be phosphorylated by clathrin-coated vesicles [7].

Chemical compound and disease context of RGS19

• We have explored the selectivity of chick GAIP in electrophysiological assays of two G(o)-mediated forms of Ca(2+) channel inhibition produced by gamma-aminobutyric acid in chick dorsal root ganglion neurons, voltage-independent inhibition (mediated by G(o)alpha) and voltage-dependent inhibition (mediated by G(o)betagamma) [3].

Biological context of RGS19

• GAIP/RGS19 alternative splicing patterns are differentially expressed in various tissues [8].
• In both human and mouse, the GAIP/RGS19 gene is composed of seven exons [8].
• Purified, recombinant RGSZ1, RET-RGS1, and GAIP each accelerated the hydrolysis of Galphaz-GTP over 400-fold with Km values of approximately 2 nM [9].
• We report the genomic structure and functional activities of the promoter regions of the human opioid-receptor-like gene ORL1 and its 5'-adjacent gene GAIP (G alpha interacting protein) [10].
• We demonstrate herein that either of two such RGS proteins, RGS4 or GAIP, attenuated signal transduction mediated by endogenous receptors, G proteins, and effectors when stably expressed as tagged proteins in transfected mammalian cells [11].

Anatomical context of RGS19

• Dynamic translocation of GAIP to the plasma membrane and coassembly in a protein complex in which GIPC was a required component was dictated by D2R activation and physical interactions [12].
• RGSZ1, RET-RGS1, and GAIP share a cysteine string sequence, perhaps targeting them to secretory vesicles and allowing them to participate in the proposed control of secretion by Gz [9].
• Previously, we demonstrated that GAIP is localized on clathrin-coated vesicles (CCVs) [13].
• The reconstitution of the interaction between a heterotrimeric G protein and GAIP on CCVs provides biochemical evidence for a model whereby the G protein and its GAP are compartmentalized on different membranes and come into contact at the time of vesicle fusion [13].
• When Cos cells were transiently transfected with GAIP and metabolically labeled with [35S]methionine, two pools of GAIP--a soluble and a membrane-anchored pool--were found [14].

Associations of RGS19 with chemical compounds

• Furthermore, the only Galphai2 variant that interacted strongly with GAIP contained a replacement of the corresponding Galphai2 Switch 3 residue (Ala230) with aspartate [15].
• GAIP is a GAP or guanosine triphosphatase-activating protein that was initially discovered by virtue of its ability to bind to the heterotrimeric G protein Galphai3, which is found on both the plasma membrane (PM) and Golgi membranes [16].
• By screening a rat brain cDNA library using the yeast two-hybrid system with the C-terminus domain of the dopamine D(3) receptor (D(3)R) as bait, we characterized a new interaction with the PDZ domain-containing protein, GIPC (GAIP interacting protein, C terminus) [17].
• Accordingly, ATA challenge increased the rate of macroautophagy, whereas epidermal growth factor did not significantly affect macroautophagy and GAIP phosphorylation status [2].

Physical interactions of RGS19

• Some of RGS4 residues involved in the Galpha-RGS binding interface have similar orientations in GAIP (free form), indicating that upon binding these residues do not suffer conformational rearrangements, and therefore, their role does not seem to be restricted to Galpha interaction but also to RGS folding and stability [18].
• A chimeric G protein composed of a Galphai2 N terminus and a Galphai1 C terminus interacted as strongly with GAIP as native Galphai1, whereas a chimeric N-terminal Galphai1 with a Galphai2 C terminus did not interact [15].

Regulatory relationships of RGS19

• RGS4 and GAIP are GTPase-activating proteins for Gq alpha and block activation of phospholipase C beta by gamma-thio-GTP-Gq alpha [19].
• These results demonstrate that the GTPase-activating protein activity of GAIP is stimulated by Erk2 phosphorylation [20].

Other interactions of RGS19

• A core-promoter region functions bi-directionally for human opioid-receptor-like gene ORL1 and its 5'-adjacent gene GAIP [10].
• GAIP, a protein that specifically interacts with the trimeric G protein G alpha i3, is a member of a protein family with a highly conserved core domain [21].
• GAIP appears to interact exclusively with G alpha i3, as it did not interact with G alpha i2 and G alpha q [21].
• Using the yeast two-hybrid system we have identified a human protein, GAIP (G Alpha Interacting Protein), that specifically interacts with the heterotrimeric GTP-binding protein G alpha i3 [21].
• RGS4 was more effective than GAIP in blocking Gq-mediated activation of phospholipase Cbeta [11].

Analytical, diagnostic and therapeutic context of RGS19

• Here we investigated, by immunofluorescence labeling and deconvolution analysis, the site at which endogenous Galpha-interacting protein (GAIP) (RGS19) binds to Galphai3-YFP and its fate after activation of delta-opioid receptor (DOR) [22].
• A rat liver fraction containing vesicular carriers (CV2) was enriched (4.5x) for GAIP by quantitative immunoblotting, and GAIP was detected on some of the vesicles in the CV2 fraction by immunoelectron microscopy [13].
• In this work we used cell fractionation and immunocytochemistry to determine with what particular membranes GAIP is associated [16].
• By immunoprecipitation carried out on [(32)P]orthophosphate-labeled AtT-20 pituitary cells stably expressing GAIP, (32)P-labeling was associated exclusively with the membrane pool of GAIP [7].
• G alpha interacting protein (GAIP),which stimulates the GTPase activity of the Galphai3 protein and favours macroautophagic sequestration in HT-29 cells,was shown, by immunofluorescence studies using confocal microscopy, to be confined to the cytoplasm [23].

References