BOVINE SRY GENE LOCUS - CLONING AND TESTICULAR EXPRESSION

The bovine SRY gene was cloned by a combination of anchored polymerase chain reaction (PCR) amplification of genomic restriction fragments and reverse transcription-PCR (RT-PCR) of testicular RNA. We report 1800 bp of combined genomic and cDNA sequences including 311 bp of 5' upstream sequences, an open reading frame of 687 bp, and 202 bp of sequences corresponding to the 3' end of the mRNA. The bovine SRY gene encodes a deduced (predicted on the basis of a cDNA sequence) protein product of 229 amino acids, with sequence conservation between species, notably in the region of the high-mobility group (HMG) domain or HMG box. Outside of the HMG box, the bovine SRY structure shows greater resemblance to the human SRY than to the mouse Sry. As with human SRY promoter sequences, putative binding sites for sp1 and for SRY itself are seen in the bovine SRY promoter region. Unlike the human SRY promotor, CAAT and TATA box motifs are present in the bovine sequences. Southern analysis and PCR amplification of male and female bovine genomic DNA show that the described sequences are specific to the Y chromosome. Northern analysis of bull testicular RNA demonstrated low levels of expression of the bovine SRY gene in adult testes with a major poly(A) species at 1.9 kb. RT-PCR amplification of bull testicular RNA revealed multiple sites of polyadenylation, but sequencing showed no consensus polyadenylation signal.