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Title: Conversion of human choriogonadotropin into a follitropin by protein engineering

Human reproduction is dependent upon the action of follicle-stimulating hormone (hFSH), luteinizing hormone (hLH), and chorionic gonadotropin (hCG). While the {alpha} subunits of these heterodimeric proteins can be interchanged without effect on receptor-binding specificity, their {beta} subunits differ and direct hormone binding to either LH/CG or FSH receptors. Previous studies employing chemical modifications of the hormones, monoclonal antibodies, or synthetic peptides have implicated hCG {beta}-subunit residues between Cys-38 and Cys-57 and corresponding regions of hLH{beta} and hFSH{beta} in receptor recognition and activation. Since the {beta} subunits of hCG or hLH and hFSH exhibit very little sequence similarity in this region, the authors postulated that these residues might contribute to hormone specificity. To test this hypothesis the authors constructed chimeric hCG/hFSH {beta} subunits, coexpressed them with the human {alpha} subunit, and examined their ability to interact with LH and FSH receptors and hormone-specific monoclonal antibodies. Surprisingly, substitution of hFSH{beta} residues 33-52 for hCG{beta} residues 39-58 had no effect on receptor binding or stimulation. However, substitution of hFSH{beta} residues 88-108 in place of the carboxyl terminus of hCG{beta} (residues 94-145) resulted in a hormone analog identical to hFSH in its ability to bind and stimulate FSH receptors. The altered binding specificity displayedmore » by this analog is not attributable solely to the replacement of hCG{beta} residues 108-145 or substitution of residues in the determinant loop located between hCD{beta} residues 93 and 100.« less
Authors:
; ;  [1]
  1. (Univ. of Medicine and Dentistry of New Jersey, Piscataway (United States))
Publication Date:
OSTI Identifier:
5043488
Resource Type:
Journal Article
Resource Relation:
Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (United States); Journal Volume: 88:3
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; GONADOTROPINS; GENETIC ENGINEERING; PEPTIDE HORMONES; AMINO ACID SEQUENCE; DOSE-RESPONSE RELATIONSHIPS; FSH; IMMUNOLOGY; IODINE 125; LH; MONOCLONAL ANTIBODIES; PLASMIDS; REPRODUCTION; TESTOSTERONE; ANDROGENS; ANDROSTANES; ANTIBODIES; BETA DECAY RADIOISOTOPES; BIOTECHNOLOGY; CELL CONSTITUENTS; DAYS LIVING RADIOISOTOPES; ELECTRON CAPTURE RADIOISOTOPES; HORMONES; HYDROXY COMPOUNDS; INTERMEDIATE MASS NUCLEI; INTERNAL CONVERSION RADIOISOTOPES; IODINE ISOTOPES; ISOTOPES; KETONES; MOLECULAR STRUCTURE; NUCLEI; ODD-EVEN NUCLEI; ORGANIC COMPOUNDS; PITUITARY HORMONES; PROTEINS; RADIOISOTOPES; STEROID HORMONES; STEROIDS 550201* -- Biochemistry-- Tracer Techniques