The mammalian gene encoding the α subunit of the Go protein generates by alternative splicing two isoforms, αo1 and αo2, which differ in their carboxy-terminal region. We report here the cloning of a Xenopus cDNA (XGαo1) which encodes a protein corresponding to the mammalian αo1 isoform. In its 3′ untranslated region, the transcript contains a repetitive motif made up of dinucleotide AT repeats. By RT-PCR amplification, we showed that XGαo1 transcripts are both maternal and zygotic. As αo2 transcripts have been shown to be maternal and devoid of AT repeats, the repetitive motif could play a role in the differential expression of each isoform.