Disease relevance of GNG12

• Pertussis toxin delayed the onset of inhibition by GTP gamma S but did not prevent the inhibitory effect. alpha o-GTP gamma S or alpha o-GDP had little effect on PLC activity. alpha i-GTP gamma S and alpha i-GDP produced a 15% inhibition of PLC activity [1].
• Biochemical characterization of the purified ram p25 revealed that the profile of [35S]GTP gamma S-binding activity was almost the same as that of recombinant ram p25 expressed in E. coli [2].

High impact information on GNG12

• Activation of IK.ACh by recombinant G alpha-GTP gamma S was observed, but this was probably due to release of GTP gamma S from the protein [3].
• Release of bound [35S]GTP gamma S from ARF3 required the presence of both GEP and unlabeled GTP or GTP gamma S; GDP was much less effective [4].
• In the presence of 0.6-0.8 mM MgCl2 and 1 mM EDTA, binding of guanosine 5'-[gamma[35S]thio]triphosphate ([35S]GTP gamma S) by ARF1 and ARF3 was equally high without and with GEP [4].
• The strongest effect was observed for gamma S, followed by h gamma Srec, gamma E, gamma A-F, gamma D, gamma B. Moreover, fluorescence properties of alpha-crystallins in the presence of bound beta(LOW)-and gamma-crystallins indicated that the formation of beta(LOW)/alpha- or gamma/alpha-crystallin complexes involved various binding sites [5].
• In each case, binding appeared specific as judged by competition of unlabeled G beta gamma with radiolabeled G beta gamma and inhibition of binding by antigenic peptide or G alpha-GDP, but not G alpha-GTP gamma S (guanosine 5'-3-O-(thio)triphosphate) [6].

Biological context of GNG12

• The carboxyl-terminal G alpha tGTP gamma S binding site of P gamma is different from but adjacent to its PDE inhibitory site [7].
• The alpha T.GDP complex also is capable of inhibiting the alpha T.GTP gamma S-stimulated cyclic GMP hydrolysis by the native PDE [8].
• The inactive (GDP-bound) form of the alpha-subunits appears to be the preferred substrate, with the phosphorylation being significantly reduced in alpha o and alpha i upon the binding of guanosine 5'-O-thiotriphosphate (GTP gamma S) and completely eliminated in the pure alpha-GTP gamma S complex of transducin [9].
• Phospholipid-bound ARFGTP gamma S can also stably interact with and activate the catalytic subunit of cholera toxin, suggesting that ARFGTP provides a membrane anchor for cholera toxin and thereby facilitates its access to membrane-bound substrates [10].
• Examination of the kinetics of dissociation of guanosine 5'-3-O-(thio)triphosphate (GTP gamma S) suggests that G226A Gs alpha is incapable of assuming the conformation necessary for high affinity binding of Mg2+ to the alpha subunit-GTP gamma S complex [11].

Anatomical context of GNG12

• Removal of PDE's membrane-binding domain by limited trypsin digestion eliminated both the binding of PDE to vesicles and the ability of PDE to be activated by T alpha-GTP gamma S and membranes [12].
• Using [35S]guanosine 5'-O-(3-thiotriphosphate) ([35S]GTP gamma S) as the binding ligand, purified myelin from bovine brain was found to contain approximately half the binding activity of whole white matter (138 +/- 9 vs. 271 +/- 18 pmol/mg of protein) [13].
• Salicylate (3 mM) and piroxicam (50 microM) reduced [35S]GTP gamma S binding to purified plasma membranes [65 +/- 3.7 and 75 +/- 5.3% (P < 0.003) of control, respectively] [14].
• [35S]GTP gamma S-binding activity is detected in the cytosol fraction but this activity is one-sixth to one-eighth of that of the crude membrane fraction [15].
• [35S]ATP gamma S binding to intact bovine aortic endothelial cells was competed by ATP gamma S (Kd: 1.0 +/- 0.5 microM; mean +/- S.D.), but not by 2-MeSATP and UTP, indicating that these binding sites are neither the P2Y nor the P2U receptors [16].

Associations of GNG12 with chemical compounds

• The 2.2 A crystal structure of activated rod transducin, Gt alpha.GTP gamma S, shows the bound GTP gamma S molecule occluded deep in a cleft between a domain structurally homologous to small GTPases and a helical domain unique to heterotrimeric G proteins [17].
• Phosphatidylcholine vesicles also will enhance the alpha T.GTP gamma S-stimulated PDE activity (1.5-2-fold) relative to that measured in the absence of a lipid milieu [18].
• [35S]GTP gamma S binding to 22K G was inhibited by pretreatment with N-ethylmaleimide [19].
• This potentiation by AS/7 cannot be attributed simply to an increase in the apparent affinity of alpha T.GTP gamma S for the effector enzyme, nor to an increased affinity of the enzyme for the substrate cyclic GMP [18].
• Reinsertion of these partially purified receptor preparations into phospholipid vesicles reconstituted guanine nucleotide-sensitive high affinity agonist binding, agonist-promoted GTPase and 35S-labeled guanosine 5'-O-(thiotriphosphate) [( 35S]GTP gamma S) binding activity in these preparations [20].

Physical interactions of GNG12

• In these animals we studied several highly polymorphic genetic systems such as haemoglobin, albumin, the BoLA Complex (class I and II) and the gamma S crystallin gene [21].

Other interactions of GNG12

• When the AS/7 is papain-treated to yield monovalent antibody molecules, complexation between these monovalent antibodies and alpha T still occurs (as reflected by the ability of these antibodies to block rhodopsin-alpha T coupling); however, the potentiation of the alpha T.GTP gamma S-stimulated PDE activity is lost [18].
• Receptor-catalyzed activation of Gq/11 by GTP gamma S, measured as the ability to activate purified phospholipase C-beta 1, paralleled receptor-catalyzed [35S]GTP gamma S binding [22].

Analytical, diagnostic and therapeutic context of GNG12

• Unmyristoylated ARFGTP gamma S cosediments with phospholipid vesicles and totally binds to phospholipid-cholate micelles, as seen by gel filtration chromatography [10].
• The basic strategy was that the materials were initially incubated with [35S]GTP gamma S at 37 degrees C. After 4 degrees C incubation in the wells of an ELISA plate precoated with G-protein antibodies, the radioactivity of each well was counted [23].
• Purified rhodopsin is recombined with a G-protein containing extract in the presence of [35S]GTP gamma S and after incubation the reaction is stopped by rapid cooling and filtration [24].

References