Description and references

Glycoprotein hormone synthesized by chorionic tissue of the placenta; found in blood and urine during pregnancy. Maintains the function of the corpus luteum and stimulates ovarian steroid secretion in the early stages of gestation. Bioactivity closely resembles that of luteinizing hormone. Structurally similar to LH, FSH, and TSH, q.q.v., all are dimers consisting of noncovalently linked α and β subunits. Within a species, the α-subunits of the four hormones are essentially identical, while the β-subunits, although exhibiting varying degrees of homology, are unique and believed to be responsible for the biological specificity of the individual hormones. Produced by trophoblastic cell neoplasms and used in the diagnosis and management of trophoblastic malignancies. Also produced by cancer cells of various histological types. Discovery in human pregnancy urine: S. Aschheim, B. Zondek, Klin. Wochenschr. 6, 1322 (1927); in serum of pregnant mares: H. H. Cole, G. H. Hart, Am. J. Physiol. 93, 57 (1930). Isoln of human CG: B. Zondek, S. Aschheim, Klin. Wochenschr. 7, 831 (1928); S. Gurin et al., J. Biol. Chem. 128, 525 (1939); P. A. Katzman et al., ibid. 148, 501 (1943). Review of early literature: J. A. Loraine, J. Reprod. Fertil. 12, 23-31 (1966). Purification and physicochemical properties: O. P. Bahl, J. Biol. Chem. 244, 567 (1969). Isoln of α and β subunits: N. Swaminathan, O. P. Bahl, Biochem. Biophys. Res. Commun. 40, 422 (1970); F. J. Morgan, R. E. Canfield, Endocrinology 88, 1045 (1971). Amino acid sequence of α-subunit: R. Bellesario et al., J. Biol. Chem. 248, 6796 (1973); of the β-subunit: R. B. Carlsen et al., ibid. 6810; F. J. Morgan et al., ibid. 250, 5247 (1975). Crystal structure: A. J. Lapthorn et al., Nature 369, 438 (1994). Purification using HPLC: M. A. Chlenov et al., J. Chromatogr. 631, 261 (1993). Comparison of gonadotropins of various species: J. G. Pierce, T. F. Parsons, Annu. Rev. Biochem. 50, 465-495 (1981). Review of biosynthesis: R. O. Hussa, Endocr. Rev. 1, 268-294 (1980). Diagnostic use as a tumor marker: L. A. Cole et al., Cancer Res. 48, 1356 (1988); D. L. Blithe et al., Trends Endocrinol. Metab. 1, 394 (1990). Secretion in normal, nonpregnant humans: W. D. Odell et al., ibid. 418. Synthesis and expression by tumor cells: H. F. Acevedo et al., Cancer 76, 1467 (1995). Review of clinical assay methods: R. J. Norman et al., Ann. Clin. Biochem. 27, 183-194 (1990). Review of structure, secretion and bioactivity of equine CG: B. D. Murphy, S. D. Martinuk, Endocr. Rev. 12, 27-44 (1991).

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