G proteins subtypes

Krieger J., Schmitt A.L., Gudermann T., Schultz G., et al. (1999). Selective activation of G-protein subtypes in the vomeronasal organ upon stimulation with urine-derived compounds. J Biol Chem 274, 4655-4662. 

Bernard, R., Lydic, R. Baghdoyan, H. A. (2006). Hypocretin (orexin) receptor subtypes differentially enhance acetylcholine release and activate G protein subtypes in rat pontine reticular formation./. Pharmacol. Exp. Ther. 317, 163-71. 

Adenylyl cyclase subtypes are also regulated by Py subunits. The regulation by GPy varies dramatically with the different forms of adenylyl cyclase [1, 2, 18]. In the presence of Gas, the addition of GPy complexes inhibits AC1 and AC8 but stimulates AC2, AC4, and AC7. The concentration of GPy required for its inhibitory effect on AC1 is higher than the concentration of free Gas required to activate this enzyme. This indicates that dissociation of Gpy from other, more abundant G proteins (e.g. Gai and G o) would be the primary source of GPy for this type of inhibition to occur in brain that expresses relatively high levels of these G protein subtypes. The effect of GPy on AC1 and AC8 is notable in that the inhibition is more... 

Ward RJ, Milligan G (1999) An Asp79Asn mutation of the a2A-aagonist activation of individual Gia-family G protein subtypes. FEBS Lett 462 459-463... 

Schandar M., Laugwitz K. L., Boekhoff I., Kroner C., Guderman T., Schultz G. and Breer H. (1998) Odorants selectively activate distinct G protein subtypes in olfactory cilia. 

There are two principal groups of receptors for epinephrine and NE, so-called adrenoreceptors, which are divided into a- and P-adrenoreceptors. a-adrenoreceptors are subdivided into oti and oc2, whereas the P-adrenoreceptors into Pi, P2 and P3. All the adrenoreceptors are coupled to different G protein subtypes. More specifically, oci-adrenoreceptors is coupled to Gq, a2-adrenoreceptors to Gi, and all the P-adrenoreceptors to Gs. Briefly, activation of Gs and G, stimulates and reduces the production of cAMP, respectively. cAMP functions as a second messenger that can activate the protein kinase A (PKA), which in turn, can transfer the signals to the nucleus. 

DELTA OPIOID RECEPTOR ACTIVATION OF G PROTEIN SUBTYPES... 

Wu et al. also demonstrated selectivity in the coupling of a,-AR subtypes to different G protein subtypes [44]. a,-ARs couple to PLC through the G, class of G proteins which include G , Gn, G,4, and G,b (as well as the recently described G, not used in this study). 

Figure 7. G protein subtypes mediating InsP response to NE in Cos-7 cells transfected with different subtypes as determined by Wu and colleagues [44].

Kleuss C, Hescheler J, Ewel C, Rosenthal W, Schultz G, Wittig B (1991) Assignment of G-protein subtypes to specific receptors inducing inhibition of calcium currents. Nature 353 43-48... 

In recent years such antibodies have also been utilised to identify putative plant G polypeptides. In particular, initial efforts utilised antisera to the a<. peptide and identified polypeptides of Mr 33 kDa or 31 kDa [19]. Other workers used anti-Gs serum [69] which crossreacted with proteins of Mr 37 kDa and 50 kDa associated with microsomal membranes from Cucurbita pepo. Since then, antisera to a number of other G-protein subtypes, i.e. Gi , Gt , GAra , Go and Gq have been utilised with varying degrees of success [35,36,100,156,151). These data are summarised in Table 2. One problem that has arisen in some reports, is the omission of a control appropriate to the use of anti-peptide antibodies. With these reagents, artifactual cross reactions are frequently encountered, which may represent recognition of part of the peptide sequence, the crosslinking reagent or the carrier protein. An essential pre-requisite to assess fidelity of identification is the ability to block the cross reaction via preincubation of the antiserum with the synthetic peptide to which it was raised. 

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