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Isolation and Characterization of a Novel cDNA Which Identifies Both Neural‐Specific and Ubiquitously Expressed G Sα mRNAs
Author(s) -
Habecker Beth A.,
Martin Jennifer M.,
Nathanson Neil M.
Publication year - 1993
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1993.tb02177.x
Subject(s) - biology , microbiology and biotechnology , adenylyl cyclase , complementary dna , g alpha subunit , cdna library , polyadenylation , heterotrimeric g protein , alternative splicing , gene isoform , messenger rna , protein subunit , g protein , receptor , gene , genetics
Heterotrimeric G proteins consisting of α, β, and γ subunits couple sensory, hormone, and neurotransmit‐ ter receptors to intracellular and transmembrane effectors. Several splicing variants of the G s (the G protein that stimulates adenylyl cyclase) α subunit (G Sα ) have been described. Some of these couple receptors to stimulation of adenylyl cyclase and Ca 2+ channels, whereas others encode truncated proteins whose functions are not currently defined. We describe a 1321N1 human astrocytoma cDNA clone for a novel G Sα isoform isolated from astrocytoma cells (G astro ) that is identical to G Sα ‐1 with the exception of a novel 5’ sequence extending into the previously described exon 1 of G Sα , 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 G Sα 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.