At least three alternatively spliced mRNAs encoding two α subunits of the Go GTP-binding protein can be expressed in a single tissue

Philippe Bertrand, Jack Sanford, Uwe Rudolph, Juan Codina, Lutz Birnbaumer

Research output: Contribution to journalArticlepeer-review


Hybridization blot (Northern) analysis of mRNA coding for α subunits of the Go signal-transducing protein detects three bands at 5.7, 4.2, and 3.2 kilobases (kb). We showed previously that the largest is a splice variant coding for the type 2 form of the polypeptide (αo2) and the two smaller RNAs react with a probe specific for the seventh of the eight exons that code for the type 1 form (αo1). In the present work we demonstrate that the 3.2- and 4.2-kb mRNAs also result from alternative splicing, the splice site being located 31 nucleotides downstream from the termination codon of the open reading frame, and that therefore the αo mRNA is made up of at least nine exons. All three αo mRNAs are expressed in both heart and brain, more in the latter than the former, as well as in the hamster insulin-secreting tumor (HIT) cell from which the cDNAs encoding the splice variants had been cloned. In contrast, in lung and testis we found only the 5.7-kb αo2 mRNA. The same analysis was unable to detect αo-specific sequences in either kidney, pancreas (whole), spleen, or liver, while at the same time detecting strong bands for αs mRNA. A comparison of the nucleotide sequences of the 5′- and 3′-untranslated regions of the hamster cDNAs cloned here indicated that previously cloned αo cDNAs all belong to the same αo1A splice subclass derived from 3.2-kb mRNA. The comparison also revealed that the sequences of the untranslated regions are highly conserved among three species (rat, hamster, and brain). Their 3′ tails are 99.1% (HIT versus bovine, 200 known bases) and 99.7% (HIT versus rat, 229 bases) identical, and their 5′ leader sequences are 92.7% (HIT versus bovine, 165 known bases) and 90.7% (HIT versus rat, 670 bases) identical. This indicates that untranslated regions of mRNAs need not exhibit high degrees of species variation.

Original languageEnglish (US)
Pages (from-to)18576-18580
Number of pages5
JournalJournal of Biological Chemistry
Issue number30
StatePublished - Oct 25 1990
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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