N-glycosylated and unglycosylated forms of caprine trophoblast protein-1 are secreted by preimplantation goat conceptuses

Goat conceptuses secrete caprine trophoblast protein-1 (cTP-1) which is related antigenically to the abundant embryonic interferon-alpha II of sheep and cattle. Antiserum to ovine and bovine TP-1s immunoprecipitated three molecular weight classes (23,000, 21,000 and 17,000, each with two isotypes) of cTP-1 from goat conceptus culture medium. Cultures which contained tunicamycin resulted in a shift in the Mr = 23,000 and Mr = 21,000 forms to a Mr of 17,000. The Mr = 23,000 and 21,000 forms, but not the Mr = 17,000 form, bound to Concanaval in A-Sepharose and were eluted under conditions selective for glycoproteins bearing complex-type oligosaccharide(s). Thus cTP-1 is a mixture of glycosylated and unglycosylated polypeptides.