Molecular Cloning and Characterization of Complementary Deoxyribonucleic Acids Corresponding to Bovine Trophoblast Protein-1: A Comparison with Ovine Trophoblast Protein-1 and Bovine Interferon-α_II

Abstract

Bovine trophoblast protein-1 (bTP-1) is a secreted glycoprotein that consists of several forms differing slightly in mol wt and isoelectric point. It is produced by bovine conceptuses after about day 15 of pregnancy and is believed to play a key role in signalling the presence of an embryo to the mother. In this study, a series of recombinant cDNA clones corresponding to the mRNA for bTP-1 have been isolated from cDNA libraries representing day 18-19 bovine conceptus poly(A) + mRNA. Base sequencing of several cDNAs indicated that multiple mRNAs for bTP-1 exist. Northern blotting and primer extension experiments showed that the mRNAs average about 1 kilobase in length. One apparently full-length cDNA clone consisted of 1035 bases up to the beginning of the poly(A) tail. It contained an open reading frame of 195 codons which began at a position 79 bases from the 5' end. Its entire sequence was 85% identical to that of a cDNA for the immunologically related ovine trophoblast protein-1 (oTP-1) and about 79% identical to that for a bovine interferona u (IFNa M ). The highest conservation of sequence (>90%) was noted in the 3'-untranslated sequences of the bTP-1 and oTP-1 cDNAs. The deduced amino acid sequence of bTP-1 shared 80% identity with oTP-1, between 45-55% with human, rodent, porcine, and bovine IFNs of the a ( subfamily and about 70% with a bovine IFNa M . A single potential site for A/-glycosylation was noted at Asn 78 . These results show that bTP-1, like its ovine counterpart oTP-1, is structurally related to the IFNas. We suggest that