Isolation and characterization of two coho salmon gonadotropins, GTH I and GTH II.
Two gonadotropins, GTH I and GTH II, were isolated from pituitaries of spawning coho salmon (Oncorhynchus kisutch) using sequential extractions with ammonium acetate (pH 9.0) and 40% ethanol, precipitation with 80% ethanol, gel filtration chromatography (Sephadex G-100), anion-exchange chromatography (Mono-Q Sepharose), and gel filtration chromatography (Sephadex G-75). Coho salmon GTH I and GTH II stimulated steroidogenesis in vitro in a similar dose-dependent manner when incubated with either ovaries or testes of prepubertal coho salmon. An in vivo bioassay using coho salmon parr demonstrated that coho salmon GTH I and GTH II did not contain thyrotropic activity. Molecular weights were estimated by gel filtration chromatography to be 43,000 and 39,000 for GTH I and GTH II, respectively. Analysis of coho salmon GTH I and GTH II on reversed-phase high-performance liquid chromatography (rpHPLC) revealed that they consist of alpha and beta subunits with N-terminal amino acid residues of Tyr, Gly (alpha, beta of GTH I) and Tyr,Ser (alpha, beta of GTH II). Coho salmon GTH I-beta and GTH II-beta differed from each other in amino acid composition, N-terminal amino acids (Gly vs. Ser), and molecular weights in SDS-PAGE (19,000 vs. 20,000) and had a high degree of chemical similarity to chum salmon GTH I-beta and GTH II-beta, respectively. Specific rabbit antisera to the beta subunits of coho salmon GTH I and GTH II were generated. The observation of two GTHs with distinctly different chemical characteristics in coho salmon is similar to what has previously been found in chum salmon.
Swanson
P
P
School of Fisheries, University of Washington, Seattle 98195.
Suzuki
K
K
Kawauchi
H
H
Dickhoff
W W
WW
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D005260:Female; D006065:Gonadotropins, Pituitary / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D008297:Male; D008970:Molecular Weight; D010053:Ovary / Q000187:drug effects / Q000378:metabolism; D012474:Salmon / Q000378:metabolism*; D013256:Steroids / Q000096:biosynthesis; D013737:Testis / Q000187:drug effects / Q000378:metabolism
D000596:Amino Acids; D006065:Gonadotropins, Pituitary; D013256:Steroids; C057763:gonadotropin- pituitary, beta-subunit I, salmon