The two mRNA forms for the type I alpha regulatory subunit of cAMP-dependent protein kinase from human testis are due to the use of different polyadenylation site signals.

Using a cDNA probe for the type I alpha regulatory subunit, two mRNA species (1.5 and 3.0 kb in length) were detected in human testis. From a human testis cDNA-library a 3.0 kb clone, containing the entire reading frame of the protein, was isolated. Comparison of the nucleotide sequence of this clone to the sequence of a 1.5 kb cDNA clone earlier reported, showed that the longer clone was identical to the shorter but extended another 1.5 kb in the 3' end. Sequencing data together with Northern blot analysis indicated that the two mRNA species for human type I alpha regulatory subunit were generated from the same gene by the use of different polyadenylation site signals.