Synthesis and processing of ovine trophoblast protein-1 and bovine trophoblast protein-1, conceptus secretory proteins involved in the maternal recognition of pregnancy.
Ovine and bovine trophoblast protein-1 (oTP-1 and bTP-1) are newly discovered proteins produced by embryonic tissues for a limited period in early gestation. They appear to act as agents that prevent regression of the corpus luteum during early pregnancy in the ewe and cow. Ovine TP-1 [mol wt (Mr), 17,000] consists of three or four isoelectric variants (pI 5.4-5.7), whereas bTP-1, which cross-reacts with antiserum to oTP-1, is found as two predominant Mr classes (Mr, 22,000 and 24,000), each with several isoelectric variants (in the pI range 6.3-6.8). Cell-free translation of ovine conceptus mRNA yields pre-oTP-1 also consists of three or four isoelectric variants, assumed to have arisen by translation of multiple mRNA species. Ovine TP-1 is not glycosylated. When bovine conceptus mRNA is translated, a group of four or five isoforms of pre-bTP-1 are generated, each with a Mr of 19,000. In the presence of microsomes the Mr shifts upward to about 21,500. Bovine conceptuses cultured in presence of either [3H]glucosamine or [3H]mannose incorporate label into both size classes of bTP-1 (Mr, 22,000 and 24,000). Culture in presence of [35S]methionine and tunicamycin gave rise to a nonglycosylated form of bTP-1 with an apparent Mr of 18,000. Treatment of [35S]methionine-labeled bTP-1 with either endoglycosidase-H or peptide:N-glycosidase F yielded products with Mr of 17,000 and 16,000, respectively. bTP-1, although functionally and structurally related to oTP-1, appears to be a glycoprotein carrying at least two Asn-linked oligosaccharides. The two Mr classes of bTP-1 arise as a result of differences in either the number or structure of the carbohydrate chains. Like oTP-1, bTP-1 is probably translated from multiple mRNA species.
Anthony
R V
RV
Department of Animal Science, University of Missouri, Columbia 65211.
Helmer
S D
SD
Sharif
S F
SF
Roberts
R M
RM
Hansen
P J
PJ
Thatcher
W W
WW
Bazer
F W
FW
D000818:Animals; D002417:Cattle / Q000502:physiology*; D005260:Female; D007370:Interferon Type I; D008970:Molecular Weight; D009924:Organ Culture Techniques; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D011270:Pregnancy, Animal / Q000378:metabolism*; D014176:Protein Biosynthesis; D012313:RNA / Q000302:isolation & purification; D012333:RNA, Messenger / Q000235:genetics; D012756:Sheep / Q000502:physiology*; D013045:Species Specificity; D014327:Trophoblasts / Q000378:metabolism*
D007370:Interferon Type I; D011257:Pregnancy Proteins; D012333:RNA, Messenger; C020947:interferon tau; D012313:RNA