Isolation and characterization of a novel cDNA which identifies both neural-specific and ubiquitously expressed GS alpha mRNAs.
Heterotrimeric G proteins consisting of alpha, beta, and gamma subunits couple sensory, hormone, and neurotransmitter receptors to intracellular and transmembrane effectors. Several splicing variants of the GS (the G protein that stimulates adenylyl cyclase) alpha subunit (GS alpha) have been described. Some of these couple receptors to stimulation of adenylyl cyclase and Ca2+ channels, whereas others encode truncated proteins whose functions are not currently defined. We describe a 1321N1 human astrocytoma cDNA clone for a novel GS alpha isoform isolated from astrocytoma cells (G(astro)) that is identical to GS alpha-1 with the exception of a novel 5' sequence extending into the previously described exon 1 of GS alpha, a single base change, and an alternative polyadenylation site. Analysis by northern blotting and reverse transcription/PCR confirms the presence of an mRNA corresponding to this cDNA in astrocytoma cells. Additional northern analysis indicates that G(astro) recognizes two novel GS alpha mRNAs in the rat: a 2.0-kb mRNA expressed only in neural and neuroendocrine tissues and a 1.8-kb mRNA that is ubiquitously expressed. Functional analysis of G(astro) is complicated by the apparent insertion of alphoid satellite DNA into the transcription unit. The resulting cDNA encodes a truncated protein that may be translated from the methionine in exon 2 as previously described.
Habecker
B A
BA
Department of Pharmacology, University of Washington School of Medicine, Seattle 98195.
Martin
J M
JM
Nathanson
N M
NM
D000595:Amino Acid Sequence; D000818:Animals; D001254:Astrocytoma / Q000737:chemistry; D001483:Base Sequence; D015152:Blotting, Northern; D004247:DNA / Q000737:chemistry / Q000302:isolation & purification*; D019204:GTP-Binding Proteins / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D012260:Ribonucleases; D017421:Sequence Analysis; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; D004247:DNA; D012260:Ribonucleases; D019204:GTP-Binding Proteins