Identification of regions of the follitropin (FSH) beta-subunit that interact with the N-terminus region (residues 9-30) of the FSH receptor.
We have recently identified a region, N-terminus residues 9-30, in the extracellular domain of the follicle-stimulating hormone (FSH) receptor capable of binding FSH, but not luteinizing hormone (LH) or thyroid-stimulating hormone (FSH) (Dattatreyamurty and Reichert (1992) Mol. Cell. Endocrinol. 87, 9-17). The objectives of the present study were to examine the interaction between a synthetic peptide corresponding to this receptor sequence and the beta-subunit of FSH, and to identify which FSH-beta regions are involved in the interaction. FSH-beta subunit and synthetic FSH-beta peptides 1-15, 71-85 and 101-111 effectively bound 125I-labeled FSH rec-(9-30) peptide, and binding was inhibited by excess unlabeled FSH receptors. Scatchard analysis indicated that the synthetic FSH-beta peptides had affinities for FSH rec-(9-30) peptide in the order of 10(6) M-1 (Ka), with the sum of individual peptide affinities (Ka = 1.21 x 10(7) M-1) closely approximating that of the intact beta-subunit (1.02 x 10(7) M-1). Polyclonal antibodies raised against FSH rec-(9-30) peptide completely inhibited the binding of 125I-labeled receptor peptide to hFSH, hFSH-beta, and hFSH-beta peptides 1-15, 71-85 and 101-111. Our results indicate that recognition of FSH-beta by N-terminus region (9-30) of the FSH receptor involves contact with residues in three discontinuous binding regions on FSH-beta.(ABSTRACT TRUNCATED AT 250 WORDS)
Dattatreyamurty
B
B
Department of Biochemistry and Molecular Biology, Albany Medical College, NY 12208.
Reichert
L E
LE
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D005640:Follicle Stimulating Hormone / Q000737:chemistry / Q000378:metabolism*; D037201:Follicle Stimulating Hormone, beta Subunit; D008297:Male; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000276:immunology / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D011962:Receptors, FSH / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D011974:Receptors, LH / Q000737:chemistry; D017386:Sequence Homology, Amino Acid
D037201:Follicle Stimulating Hormone, beta Subunit; D010446:Peptide Fragments; D011962:Receptors, FSH; D011974:Receptors, LH; D005640:Follicle Stimulating Hormone