Alternative promoter and 5' exon generate a novel Gs alpha mRNA.

Y Ishikawa,C Bianchi,B Nadal-Ginard,C J Homcy

doi:10.1016/s0021-9258(19)38910-0

Abstract

Several species of mRNA have been shown to encode the alpha subunit of the stimulatory GTP-binding regulatory protein, Gs alpha. The various Gs alpha mRNAs are generated through alternative splicing of a single precursor RNA and through the use of alternative acceptor splice sites. We now report the existence of a Gs alpha mRNA that uses a previously unidentified promoter and leading exon (termed exon 1'). In both the canine and human Gs alpha genes, exon 1' is located 2.5 kilobases 5' of exon 1. Exon 1' does not contribute an in-frame ATG, and thus its mRNA encodes a truncated form of Gs alpha. Initiation of translation is predicted to begin at an AUG in exon 2, as demonstrated both by in vitro translation and COS cell expression studies.

Highlights

02114 and the YDepartment of Pediatrics, Physiology and Biophysics, Harvard Medical School and Department of Cardiology, Howard Hughes Medical Institute, Children’s Hospital, Boston, Massachusetts
We report the existence of a G.a mRNA that uses a previously unidentified promoter and leading exon
The LYsubunit appears to play the principal role in signal transduction, whereas the /3 and y subunits appear to be involved in modulating the activity of the signal transduction pathway

Summary

Introduction

A variety of tissues contain two major forms of G,ol, which are encoded by mRNAs generated by alternative splicing of exon 3; inclusion of this exon results in the insertion of 15 amino acid residues (3). To characterize the exon(s) containing this sequence and not previously identified as part of the G,cr gene, we screened a canine genomic DNA library in EMBL3 with a 170-bp fragment of the sequence unique to cDNA 6C.

Results

Conclusion