Structural characterization of a follicle-stimulating hormone action inhibitor in porcine ovarian follicular fluid. Its identification as the insulin-like growth factor-binding protein.
Recently, an inhibitory polypeptide that could block the follicle-stimulating hormone-induced estradiol and progesterone production in rat ovary granulosa cells has been isolated from porcine ovarian follicular fluid. Amino-terminal sequence analysis of the purified inhibitor suggests that it could be the porcine congener of the 53-kDa subunit of the growth hormone-dependent insulin-like growth factor binding protein (IGF-BP3). Using amino acid sequence information derived from the purified inhibitor to construct oligonucleotide probes, we have now identified the complementary deoxyribonucleic acids (cDNAs) encoding the inhibitory polypeptide from a porcine liver and a porcine ovary library. The nucleotide and predicted amino acid sequences revealed that the cDNAs indeed encode the porcine homolog of the recently characterized human IGF-BP3. The mature polypeptide consists of 266 amino acids, which is 2 amino acids longer than the human sequence. Between the two species, there are 42 amino acid substitutions, but the 18 cysteines and the three Asn-linked glycosylation sites are totally conserved. A single mRNA species of 2.6 kilobases encoding the IGF-BP3 was detected in porcine gonadal, brain, and liver tissues by Northern analysis.
Department of Molecular Endocrinology, Whittier Institute for Diabetes and Endocrinology, La Jolla, California 92037.
S
S
Shimasaki
M
M
Shimonaka
M
M
Ui
S
S
Inouye
F
F
Shibata
N
N
Ling
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D004958:Estradiol / Q000096:biosynthesis*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D015723:Gene Library; D005796:Genes; D018969:Insulin-Like Growth Factor Binding Proteins; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes / Q000096:biosynthesis; D006080:Ovarian Follicle / Q000187:drug effects / Q000378:metabolism*; D011374:Progesterone / Q000096:biosynthesis*; D012689:Sequence Homology, Nucleic Acid; D013552:Swine
D002352:Carrier Proteins; D018969:Insulin-Like Growth Factor Binding Proteins; D015345:Oligonucleotide Probes; D011374:Progesterone; D004958:Estradiol; D005640:Follicle Stimulating Hormone; D004247:DNA