Conveys a signal from an upstream receptor or intracellular signal transducer, converting the signal into a form where it can ultimately trigger a change in the state or activity of a cell.
Proc. Natl. Acad. Sci. U.S.A. 85, 5384-5388 (1988)[PubMed:2456569]
We have isolated cDNA clones from rat C6 glioma cells coding for several guanine nucleotide-binding regulatory protein (G protein) alpha subunits (G alpha). The cDNA clones were then used to isolate human chromosomal genes. Among human genomic clones isolated by cross-hybridization with the rat cDNA for the alpha subunit of the inhibitory G protein Gi2, termed Gi2 alpha, a clone designated lambda HGi62 was found to contain a sequence that is highly homologous but distinct from any of the known G alpha sequences, and we have tentatively designated this sequence Gx alpha. We have searched a rat brain cDNA library with the Gx alpha sequence and isolated a cDNA clone containing a rat sequence similar to human Gx alpha. The cDNA contained a single open reading frame of 1065 nucleotides coding for a protein of 355 amino acids with a calculated molecular weight of 40,879. The amino acid sequence of rat Gx alpha shows 66% and 40% similarity with rat Gi2 alpha and rat Gs alpha (the alpha subunit of the stimulatory G protein), respectively. By RNA blot hybridization analysis, mRNA of approximately 3.2 kilobases was detected mainly in brain. Interestingly, the deduced amino acid sequence of Gx alpha predicts that the Gx alpha protein may be refractory to modification by pertussis toxin since the cysteine residue in the fourth position from the C terminus of pertussis toxin-sensitive G alpha is replaced by isoleucine.
Conveys a signal across a cell to trigger a change in cell function or state. A signal is a physical entity or change in state that is used to transfer information in order to trigger a response.
The series of molecular signals generated as a consequence of a G-protein coupled receptor binding to its physiological ligand, where the pathway proceeds through inhibition of adenylyl cyclase activity and a subsequent decrease in the concentration of cyclic AMP (cAMP).
The series of molecular signals generated as a consequence of a G-protein coupled receptor binding to its physiological ligand, where the pathway proceeds through activation or inhibition of adenylyl cyclase activity and a subsequent change in the concentration of cyclic AMP (cAMP).
A series of molecular signals that proceeds with an activated receptor promoting the exchange of GDP for GTP on the alpha-subunit of an associated heterotrimeric G-protein complex. The GTP-bound activated alpha-G-protein then dissociates from the beta- and gamma-subunits to further transmit the signal within the cell. The pathway begins with receptor-ligand interaction, or for basal GPCR signaling the pathway begins with the receptor activating its G protein in the absence of an agonist, and ends with regulation of a downstream cellular process, e.g. transcription.
Proc. Natl. Acad. Sci. U.S.A. 85, 3066-3070 (1988)[PubMed:3129724]
Recent molecular cloning of cDNA for the alpha subunit of bovine transducin (a guanine nucleotide-binding regulatory protein, or G protein) has revealed the presence of two retinal-specific transducins, called Tr and Tc, which are expressed in rod or cone photoreceptor cells. In a further study of G-protein diversity and signal transduction in the retina, we have identified a G-protein alpha subunit, which we refer to as Gz alpha, by isolating a human retinal cDNA clone that cross-hybridizes at reduced stringency with bovine Tr alpha-subunit cDNA. The deduced amino acid sequence of Gz alpha is 41-67% identical with those of other known G-protein alpha subunits. However, the 355-residue Gz alpha lacks a consensus site for ADP-ribosylation by pertussis toxin, and its amino acid sequence varies within a number of regions that are strongly conserved among all of the other G-protein alpha subunits. We suggest that Gz alpha, which appears to be highly expressed in neural tissues, represents a member of a subfamily of G proteins that mediate signal transduction in pertussis toxin-insensitive systems.
Recently, a cDNA coding for a novel G protein alpha-subunit, Gz-alpha, was isolated from a human retinal cDNA library and shown by Northern blot analysis to be expressed at high levels in neural tissues. We have prepared affinity-purified antibodies specifically directed against synthetic Gz-alpha peptides and employed immunohistochemical methods to map the localization of Gz-alpha in human, bovine, and murine retina and brain. By light microscopy, Gz-alpha was localized to the cytoplasm of neurons, with predominant reactivity in ganglion cells of the retina, Purkinje cells of the cerebellum, and most neurons of the hippocampus and cerebral cortex. Reactivity was confined to perikaryon, dendrites, and a very short segment of proximal axons, except for the retinal ganglion cells, in which the axons in the nerve fiber layer showed intense Gz-alpha immunoreactivity proximal to the lamina cribrosa. Pre-embedding immunoelectron microscopy demonstrated the presence of focal Gz-alpha immunoreactivity on the nuclear membranes, endoplasmic reticulum, and plasma membranes of Purkinje cell perikarya and in association with microtubules in their proximal dendrites. Subcellular fractionation studies confirmed the association of Gz-alpha with plasma and intracellular membranes. The localization of Gz-alpha and its unique amino acid sequence suggest that it may have a specialized function in neural tissues.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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