The cDNA clone p16 alpha-1 for the male-specific isozyme (C-P-450(16) alpha)1 of testosterone 16 alpha-hydroxylase in livers of 129/J mice [Harada, N., & Negishi, M. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 2024-2028] and two additional full-length cDNAs overlapping with p16 alpha-1 (p16 alpha-2 and p16 alpha-16) were sequenced. p16 alpha-2 contained a single open reading frame of 1512 nucleotides, consisting of 71 base pairs of the 5'-noncoding region and 63 base pairs of the 3'-noncoding region with an additional poly(A) tract. From this DNA sequence, C-P-450(16) alpha was deduced to contain 504 amino acids with a calculated molecular mass of 56,948 daltons. p16 alpha-1 showed a nucleotide sequence identical with that of p16 alpha-2 but lacked nine amino acid residues from the N-terminus. Another cDNA clone, p16 alpha-16, also exhibited the same coding sequence with the exception of a 142 base pair deletion spanning from nucleotide 853 to nucleotide 994 of p16 alpha-2. This deletion seems to be a whole exon of this gene, resulting in a shift of reading frame and an early termination codon at 10 amino acid residues from the deletion. The expected translation product of this mRNA is calculated to be 294 amino acids and 33,300 daltons. The putative poly(A) addition signal AATAAA is present for all three clones, but there are polymorphisms in the start sites of polyadenylation.(ABSTRACT TRUNCATED AT 250 WORDS)