Goat conceptuses secrete caprine trophoblast protein-1 (cTP-1) which is related antigenically to the abundant embryonic interferon-αII of sheep and cattle. Antiserum to ovine and bovine TP-Is 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 Concanavalin 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. © 1990 Academic Press, Inc.