Characterization of the gene corresponding to bovine placental prolactin-related cDNA I: evolutionary implications.

We have previously characterized a family of transcripts, isolated from bovine placental tissue, that are related to prolactin (PRL) and are distinct from placental lactogen (PL). Here we describe a PRL-related gene that corresponds to one of these placental transcripts, bPRC-I. Restriction endonuclease mapping and sequence analysis of this gene reveal that it is distributed among five exons spanning approximately 9.2 kb. The site of transcription initiation was determined and repetitive sequences were localized in the first two introns. The nucleotide sequence of the coding region is 64% homologous to the bPRL gene and 44% homologous to the bovine growth hormone (bGH) gene. The 5'-flanking region shows no detectable homology to that of bPRL or bGH. Genomic Southern blot analysis indicates that this gene is a member of a family of PRL-related genes.