Cloning and expression of a new member of prolactin-related protein in bovine placenta: bovine prolactin-related protein-VII.

This study reports the identification and sequence of a full-length cDNA for a new member of bovine prolactin-related protein (bPRP-VII) and its quantitative and localized expression in the placenta. A full-length bPRP-VII cDNA was cloned with a 929-nucleotide open-reading-frame corresponding to a protein of 238 amino acids. The predicted amino acid sequence shares 63% homology with bPRP-I and 70% with bPRP-VI. bPRP-VII has eight cysteine residues with four disulfide bonds, which is more abundant than that of other bPRPs. RT-PCR detected bPRP-VII only in the placenta. In the placenta, mRNA was expressed in the cotyledon and intercotyledonary tissues throughout gestation. Quantitative real-time RT-PCR analysis exhibited a high expression of bPRP-VII mRNA in the fetal membrane at Day 27 of gestation. In the placentome on Day 60 of gestation, in situ hybridization analysis evidenced bPRP-VII mRNA in binucleate cells. bPRP-VII gene produced a mature protein in mammalian cell expression system. Approximately 29kDa protein was confirmed in this by the Western blot analysis with FLAG epitope tag. Expression profiles and localization were similar to those of bPRP-I. Although the functional data remain to be examined, a new member of the bPRP-VII gene was cloned. In addition to bPRP-I, bPRP-VII may take on an important functional role in implantation.