title: Purification, characterization, and molecular cloning of gonadotropin subunits of silver carp (Hypophthalmichthys molitrix).
abstract: The alpha and beta subunit of silver carp gonadotropin (scGTH-alpha and scGTH-beta) were isolated by high-performance liquid chromatography. Heterogeneity of N-terminal amino acid sequence was observed in scGTH-alpha but not in scGTH-beta. For determining the complete primary structures of scGTH-alpha and scGTH-beta, their cDNAs were cloned. Combining the data of N- and C-terminal sequences determined from proteins and the amino acid sequences deduced from cDNAs, we infer that scGTH-alpha consists of 95 and/or 93 residues and scGTH-beta consists of 115 residues. Both scGTH-alpha and scGTH-beta are glycoprotein. Their carbohydrate content is about 20 g per 100 g protein. The molecular weights of scGTH-alpha and scGTH-beta were calculated to be 12,700 and 15,700 Da, respectively. The amino acid sequences of scGTH-alpha and scGTH-beta are very similar to those of the corresponding subunit of carp GTH, different in only 2 and 4 residues, respectively. In addition, a high extent of homology (70%) was also observed between the alpha subunits of fish and mammalian GTHs. In the case of beta subunit, homology among various species of fish (75 to 98%) is much higher than that between fish and mammal (40%). These data suggest that the alpha subunit is conserved while the beta subunit is diversified during the molecular evolution of vertebrate GTH.
authors.affiliation: Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.
authors.forename: Y S
authors.initials: YS
authors.lastname: Chang
authors.forename: C J
authors.initials: CJ
authors.lastname: Huang
authors.forename: F L
authors.initials: FL
authors.lastname: Huang
authors.forename: C S
authors.initials: CS
authors.lastname: Liu
authors.forename: T B
authors.initials: TB
authors.lastname: Lo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002347:Carps / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D003530:Cyprinidae / Q000378:metabolism*; D004247:DNA / Q000235:genetics; D005399:Fishes; D006065:Gonadotropins, Pituitary / Q000235:genetics / Q000302:isolation & purification*; D008322:Mammals; D008969:Molecular Sequence Data; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
chemical_list: D006065:Gonadotropins, Pituitary; D004247:DNA