MULTIPLICITY IN TYPE-V ADENYLYLCYCLASE - TYPE V-A AND TYPE V-B

Type V mammalian adenylylcyclase cDNA was originally isolated from two animal species, the dog and rat. The amino acid sequences from the tw o species are highly homologous, but completely different in the putat ive N-terminal, cytoplasmic region. Northern blot analysis using oligo nucleotide probes unique to either of the two clones has revealed that the two forms of type V adenylylcyclase mRNA, canine form (= type V-a ) and rat form (= type V-b), are co-expressed as splicing variants in both species. Genomic Southern blot analysis has suggested that the tw o forms are the products of a single gene. When overexpressed, however , deletion of the N-terminal domain did not alter any biochemical prop erties. Thus multiple splicing variants with unique N-terminal amino a cid sequences of type V adenylylcyclase can be generated from a single gene, however, biochemical properties of these variants may not be di fferent.