The in vivo use of alternate 3- splice sites in group I introns. Nucleic Acids Res

Alternative splicing of group I Introns has been postulated as a possible mechanism that would ensure the translation of proteins encoded Into Intronic open reading frames, dlscontlnous with the upstream exon and lacking an Initiation signal. Alternate splice sites were previously depicted according to secondary structures of several group I Introns. We present here strong evidence that, In the case of Podospom anserina nad1-l4 and COX1-I7 mitochondrial Introns, alternative splicing events do occur In vivo. Indeed, by PCR experiments we have detected molecules whose sequence Is precisely that expected if the predicted alternate 3'-splice sites were used