G-protein, heterotrimer

Adjobo-Hermans, M. J., Goedhart, J. and Gadella, T. W., Jr. (2006). Plant G protein heterotrimers require dual lipidation motifs of G(alpha) and G(gamma) and do not dissociate upon activation. J. Cell Sci. 119, 5087-97. 

There are several intracellular second messengers that are activated by metabotropic receptors, also referred to as G protein-coupled receptors (Duman and Nestler 1999). These receptors couple with G proteins that are heterotrimers made up of a-, (3- and y-subunits. Interaction of the G protein heterotrimer with activated receptor increases the exchange of guanosine triphosphate (GTP) for bound guanosine diphosphate (GDP), resulting in dissociation of the heterotrimer into free a and (3y subunits that in turn can regulate second messen-... 

Ahnert-Hilger G, Schafer T, Spicher K, Grund C, Schultz G, Wiedenmann B (1994) Detection of G-protein heterotrimers on large dense core and small synaptic vesicles of neuroendocrine and neuronal cells. Eur J Cell Biol 65 26-38... 

Two crystal structures of G protein heterotrimers, GoCt/ifiiVi and Gz, 1/V/2, show two sites of interaction between Ga and the constitutive... 

Computational techniques have allowed investigators to use this extensive amount of biochemical and biophysical information to develop the available structural information, including the inactive structure of rhodopsin (T eller et al., 2001), the GDP-bound Gt heterotrimer (Lambright et al., 1994), and NMR structures of the C-termini of Gat and Gy (Kisselev and Downs, 2003 Kisselev et al., 1998), into molecular models of the receptor-G protein complex (Ciarkowski et al., 2005 Fotiadis et al., 2004 Slusarz and Ciarkowski, 2004). Since the C-terminus of Ga, a critical receptor-binding site, is absent in both structures of G protein heterotrimers (Lambright... 

Despite the fundamental importance of receptor-catalyzed G protein activation in cellular signaling, relatively little is known about this process as compared to the other regulatory events in the G protein cycle. Crystal structures of inactive rhodopsin and G protein heterotrimers provide the structural context for the meaningful interpretation of the results of the numerous biochemical and biophysical studies described in the preceding sections. Enough data has been accumulated to begin to develop rudimentary models of the receptor-G protein complex that meet some of... 

A series of empirical schemes targeting the assembly of ternary complexes on beads have been attempted with varying degrees of success (reviewed in Simons et al, 2005). In Fig. 1, the molecular assemblies that are the subject of this chapter are based on the tethering of G protein heterotrimers to beads by an epitope tag (either hexahistidine or FLAGt ) fused to the N-terminus of the y subunit, and projected away from its binding partners in three-dimensional reconstructions. 

More recent data have supported the view that the activated G protein heterotrimers can function as intact units, where conformational changes... 

As their name suggests, GPCRs bind G-proteins. A complete G-protein is a heterotri-mer of three separate proteins, consisting of a-, /3-, and -y-subunits. The a-subunit binds either guanosine diphosphate (GDP) or triphosphate (GTP). The affinity for GDP/GTP is the origin of the name G-protein. The G-protein heterotrimer binds GPCRs on both the C-terminal tail and the linker between the fifth and sixth transmembrane helices on the intracellular face of the receptor.12... 

Jarolimek W, Misgeld U (1997) GABAB receptor-mediated inhibition of tetrodotoxin-resistant GABA release in rodent hippocampal CA1 pyramidal cells. J Neurosci 17 1025-32 Jeong SW, Ikeda SR (2000a) Effect of G protein heterotrimer composition on coupling of neurotransmitter receptors to N-type Ca(2+) channel modulation in sympathetic neurons. Proc Natl Acad Sci USA 97 907-12... 

As their name suggests, G protein-coupled receptors link ligand binding to intracellular changes functionally via their engagement of three distinct proteins (Ga, Gfi, Gy) known collectively as the G-protein heterotrimer (Fig. 1). The Ga subunit of the... 

The dissociation of the G-protein heterotrimer into G and G units transmits the signal that the receptor has... 

A single hormone-receptor complex can stimulate nucleotide exchange in many G-protein heterotrimers. Thus, hundreds of G molecules are converted from their GDP into their GTP forms for each bound molecule of hormone, giving an... 

Toyoshige M, Okuya S, Rebois RV (1994) Choleragen catalyzes ADP-ribosylation of the stimulatory G protein heterotrimer, but not its free a-subunit. In Biochemistry 33 4865-4871. 

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