Evidence That the SRY Protein Is Encoded by a Single Exon on the Human Y Chromosome

To facilitate studies of the SRY gene, a 4741-bp portion of the sex-determining region of the human Y chromosome was sequenced and characterized. Two RNAs were found to hybridize to this genomic segment, one transcript deriving from SRY and the second cross-hybridizing to a pseudogene located 2.5 kb 5′ of the SRY open reading frame (ORF). Analysis of the SRY transcript using 3′ and 5′ rapid amplification and cloning of ends suggested that the entire SRY protein is encoded by a single exon. A 700-bp CpG island is located immediately 5′ of the pseudogene (and 2 kb 5′ of the SRY ORF). Within this CpG island lies the sequence CGCCCCCGC, a potential binding site for the EGR-1/WT1 family of transcription factors, some of which appear to function in gonadal development.