Ghrelin 的合成、分泌和去乙酰化
中文名称
通路描述
Ghrelin 是一种由 28 个氨基酸残基组成的肽类激素，在成熟肽的丝氨酸 -3 位进行酰化。Ghrelin 在多个组织中合成：胃黏膜的 X/A 样细胞（ghrelin 的主要来源）、下丘脑、垂体、肾上腺、甲状腺、乳腺、卵巢、胎盘、输卵管、睾丸、前列腺、肝脏、胆囊、胰腺、脂肪组织、人类淋巴细胞、脾脏、肾脏、肺、骨骼肌、心肌、静脉和皮肤。Ghrelin 结合存在于下丘脑、垂体和其他组织中的 GHS-R1a 受体。结合引起食欲刺激和生长激素的释放。循环 ghrelin 水平在饥饿期间升高，餐前达到峰值，并根据摄入的卡路里下降。
前胰高血糖素被裂解以产生胰高血糖素前体，然后由胰高血糖素 O-酰转移酶酰化，产生八酰胰高血糖素和十酰胰高血糖素。只有八酰胰高血糖素才能结合并激活 GHS-R1a 受体。未酰化的胰高血糖素（去酰化胰高血糖素）也存在于血浆中，但其功能存在争议。
酰化胰高血糖素被前体蛋白转化酶 1/3 裂解，产生成熟酰化胰高血糖素和 C-胰高血糖素。胰高血糖素的分泌受胰岛素、生长激素（促生长素）、瘦素、葡萄糖、胰高血糖素和脂肪酸的抑制。胰高血糖素的分泌受胰岛素样生长因子 -1 和 M 型激动剂的刺激。在血液中，酰化胰高血糖素由乙酰胆碱酯酶和血小板活化因子乙酰水解酶去酰化。其他酶也可能去酰化酰化胰高血糖素。
前胰高血糖素被裂解以产生胰高血糖素前体，然后由胰高血糖素 O-酰转移酶酰化，产生八酰胰高血糖素和十酰胰高血糖素。只有八酰胰高血糖素才能结合并激活 GHS-R1a 受体。未酰化的胰高血糖素（去酰化胰高血糖素）也存在于血浆中，但其功能存在争议。
酰化胰高血糖素被前体蛋白转化酶 1/3 裂解，产生成熟酰化胰高血糖素和 C-胰高血糖素。胰高血糖素的分泌受胰岛素、生长激素（促生长素）、瘦素、葡萄糖、胰高血糖素和脂肪酸的抑制。胰高血糖素的分泌受胰岛素样生长因子 -1 和 M 型激动剂的刺激。在血液中，酰化胰高血糖素由乙酰胆碱酯酶和血小板活化因子乙酰水解酶去酰化。其他酶也可能去酰化酰化胰高血糖素。
英文描述
Synthesis, secretion, and deacylation of Ghrelin Ghrelin is a peptide hormone of 28 amino acid residues which is acylated at the serine-3 of the mature peptide. Ghrelin is synthesized in several tissues: X/A-like cells of the gastric mucosa (the major source of ghrelin), hypothalamus, pituitary, adrenal gland, thyroid, breast, ovary, placenta, fallopian tube, testis, prostate, liver, gall bladder, pancreas, fat tissue, human lymphocytes, spleen, kidney, lung, skeletal muscle, myocardium, vein and skin. Ghrelin binds the GHS-R1a receptor present in hypothalamus pituitary, and other tissues. Binding causes appetite stimulation and release of growth hormone. Levels of circulating ghrelin rise during fasting, peak before a meal, and fall according to the calories ingested.
Preproghrelin is cleaved to yield proghrelin which is then acylated by ghrelin O-acyltransferase to yield octanoyl ghrelin and decanoyl ghrelin. Only octanoyl ghrelin is able to bind and activate the GHS-R1a receptor. Unacylated ghrelin (des-acyl ghrelin) is also present in plasma but its function is controversial.
Acyl proghrelin is cleaved by prohormone convertase 1/3 to yield the mature acyl ghrelin and C-ghrelin. Secretion of ghrelin is inhibited by insulin, growth hormone (somatotropin), leptin, glucose, glucagon, and fatty acids. Secretion is stimulated by insulin-like growth factor-1 and muscarinic agonists.
In the bloodstream acyl ghrelin is deacylated by butyrylcholinesterase and platelet-activating factor acetylhydrolase. Other enzymes may also deacylate acyl ghrelin.
Preproghrelin is cleaved to yield proghrelin which is then acylated by ghrelin O-acyltransferase to yield octanoyl ghrelin and decanoyl ghrelin. Only octanoyl ghrelin is able to bind and activate the GHS-R1a receptor. Unacylated ghrelin (des-acyl ghrelin) is also present in plasma but its function is controversial.
Acyl proghrelin is cleaved by prohormone convertase 1/3 to yield the mature acyl ghrelin and C-ghrelin. Secretion of ghrelin is inhibited by insulin, growth hormone (somatotropin), leptin, glucose, glucagon, and fatty acids. Secretion is stimulated by insulin-like growth factor-1 and muscarinic agonists.
In the bloodstream acyl ghrelin is deacylated by butyrylcholinesterase and platelet-activating factor acetylhydrolase. Other enzymes may also deacylate acyl ghrelin.
所含基因
19 个基因