Isolation of a novel prolactin-like cDNA clone from bovine placenta: occurrence of new family members.

A novel cDNA clone that hybridized to bovine prolactin cDNA was isolated from a bovine (Bos taurus) placental cDNA library and the nucleotide sequence was analyzed. The cDNA clone, named bPLP-III, contained one open reading frame encoding a protein consisting of 239 amino acids. The amino-acid sequence of bPLP-III is 43 and 57% homologous to bovine preprolactin and a bovine prolactin-related protein, bPRC-I, respectively, but only 23% homologous to bovine pregrowth hormone. The predicted mature protein of bPLP-III is distinct from bovine placental lactogens in amino-acid composition, suggesting that bPLP-III is the clone for a new member of prolactin-related mRNA expressed in bovine placenta.