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Free keywords:
Amino Acid Sequence; Animal; Cell Line; *Cysteine Endopeptidases/me [Metabolism]; Female; *Gonadorelin/me [Metabolism]; *Granulosa Cells/en [Enzymology]; Kinetics; Molecular Sequence Data; *Multienzyme Complexes/me [Metabolism]; Peptide Fragments/ch [Chemistry]; Peptide Fragments/me [Metabolism]; Pituitary Gland/en [Enzymology]; Rats; Support, Non-U.S. Gov't
Abstract:
The decapeptide gonadotropin-releasing hormone (GnRH) is degraded by the 20 S multicatalytic proteinase complex (proteasome EC 3.4.99.46), purified from ovarian granulosa cells, at the Tyr5-Gly6 bond and to a lesser extent at the Gly6-Leu7 bond, when incubated for 2 h at 37 degrees C. Further cleavage, at Trp3-Ser4 and Ser4-Tyr5 bonds of the neurohormone occurs only subsequently to the appearance of the initial N-terminal degradation products, (1-5)GnRH and (1-6)GnRH. Our results suggest that the sequential degradation of GnRH can serve as an important mechanism for the rapid termination of its biological activity in target cells.
