Chanat E, Duval J
Neuropeptides. 1987 Feb-Mar;9(2):177-83. doi: 10.1016/0143-4179(87)90056-4.
Enriched gonadotrophs from rat pituitaries were used to analyze the kinetics of release in vitro of the Gonadotrop Polypeptide (GP-87) under LHRH stimulation. Proteins in cultured cells were labeled with [35S]methionine. Labeling of the intracellular GP-87 pool was effected during 16 hours prior to LHRH (10(-7) M) stimulation. Proteins were analyzed either by one-dimensional SDS-PAGE (Medium content) or by two-dimensional PAGE (Cell content). An apparent half-life (intracellular catabolism + release) of 31 h for GP-87 was estimated from control cells; it dropped to 2.5 h in stimulated cells due to intense release (26% after 1 h and about 80% after 8 h of stimulation). When cells were simultaneously labeled and stimulated, the newly synthesized species appeared in the medium after a lag phase of 30 minutes, time required for synthesis and full subsequent processing. From both series of experiments, it is concluded that the hypothalamic decapeptide promotes exocytosis of the newly synthesized GP-87 well before the endogenous GP-87 pool is exhausted. Furthermore, the release of another discrete protein (B2, Mr: 81 kDa) is also stimulated by LHRH. These proteins being co-released with LH could be part of the sorting and/or routing process of hormones towards exocytosis.
来自大鼠垂体的富集促性腺激素细胞被用于分析促性腺激素多肽（GP - 87）在促黄体生成素释放激素（LHRH）刺激下的体外释放动力学。培养细胞中的蛋白质用[35S]甲硫氨酸进行标记。在LHRH（10(-7) M）刺激前16小时对细胞内GP - 87库进行标记。蛋白质通过一维SDS - PAGE（培养基成分）或二维PAGE（细胞成分）进行分析。从对照细胞中估计GP - 87的表观半衰期（细胞内分解代谢 + 释放）为31小时；在受刺激的细胞中，由于强烈释放（刺激1小时后释放26%，刺激8小时后约释放80%），半衰期降至2.5小时。当细胞同时进行标记和刺激时，新合成的物质在30分钟的延迟期后出现在培养基中，这是合成及后续完整加工所需的时间。从这一系列实验可以得出结论，下丘脑十肽在细胞内源性GP - 87库耗尽之前很久就促进了新合成的GP - 87的胞吐作用。此外，LHRH还刺激了另一种离散蛋白质（B2，分子量：81 kDa）的释放。这些与促黄体生成素共同释放的蛋白质可能是激素向胞吐作用进行分选和/或运输过程的一部分。
