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pubmed:abstractText |
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.
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