Characteristics of Growth Hormone Isolated from Sturgeon(Acipenser güldenstädti)Pituitaries*

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Abstract
GH was isolated and characterized from pituitaries of a primitive bony fish, sturgeon (Acipenser giildenstddti). Sturgeon GH was very active in a mammalian GH assay, the rat tibia test. Relative to ovine GH (NIH-GH-S9), sturgeon GH gave a parallel dose-response slope and had a potency of 0.4. Sturgeon GH also showed strong cross-reaction in a snapping turtle GH RIA, comparable to that shown by tetrapod GHs and much greater than that of modern bony fish (teleost) GH. These results, predicted by earlier experiments using pituitary extracts of related species, support the hypothesis that GHs from primitive fish are more closely related to tetrapod GHs than are teleost GHs. Chemical characterization of sturgeon GH, including amino acid terminal residue analyses, amino acid composition, molecular weight determination, and electrophoresis on polyacrylamide gels, indicated that this GH is similar to GHs previously isolated from a teleost and representative species of every tetrapod class. These data provide strong additional evidence that the molecular structure of GH has been highly conserved during evolution.