The androgen-dependent rat prostatic binding protein: comparison of the sequences in the 5′ part and upstream region of the Cl and C2 genes and analysis of their transcripts

Abstract

The complete gene encoding the polypeptide Cl of the complex androgen-controlled prostatic binding protein was isolated from a rat genomic library. A new genomic fragment (C2B) containing only the 5′ part of a C2-related gene was also purified. The segments containing exon 1 and a large part of the adjacent sequences were analysed and compared with the corresponding region of the C2A gene which has been completely sequenced previously. The high structural similarity extending over a large part of all three genomic fragments suggests the duplication of a common ancestral gene, followed by a more recent duplication of the C2-coding region. However, since the structural similarity upstream of position − 150 between C2A and C2B abruptly disappears and no transcripts specific for the C2B region can be detected in prostate RNA, we propose that at a later stage in evolution the C2B region was disrupted and inactivated. Despite the common origin and the similar regulation of the two active genes, Cl and C2A, the only obvious conserved structural element is the homopurine stretch located at position −400, although sequence motifs resembling steroid hormone response elements are present at several locations.