老鼠和人类的脂肪酰化asialoglycoprotein受体。守恒的胞质半胱氨酸残基是acylated受体亚基。
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曾庆红财政年度,魏盖尔PH
老鼠和人类的脂肪酰化asialoglycoprotein受体。守恒的胞质半胱氨酸残基是acylated受体亚基。
生物化学杂志。1996年12月13日;271 (50):32454 - 60。doi: 10.1074 / jbc.271.50.32454。
- PubMed ID
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8943311 (在PubMed]
- 文摘
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功能性鼠或人类asialoglycoprotein膜糖蛋白受体(ASGP-Rs) hetero-oligomeric积分。老鼠ASGP-R包含三个子单元,指定鼠肝凝集素(RHL) 1、2、3;人类ASGP-R包含两个子单元,HHL1 HHL2。受体都是共价改性脂肪酰化(曾,F.-Y。Kaphalia, b。安萨里,g·a·S。魏盖尔,p h(1995)生物。化学。270年,21382 - 21387;曾,F.-Y。奥卡河,j . A。魏盖尔,p h .学生物化学(1996)。 Biophys. Res. Commun. 218, 325-330). We report here that the single Cys residue in the cytoplasmic domain of each RHL or HHL subunit is fatty acylated. The degree of acylation is >/=90% per subunit. Deacylation of affinity-purified ASGP-Rs with hydroxylamine results in the spontaneous formation of dimers through reversible disulfide bonds, indicating that deacylation concomitantly generates free thiol groups. Reaction of hydroxylamine-treated ASGP-R with [14C]iodoacetamide resulted in the specific incorporation of radioactivity into all RHL and HHL subunits, verifying that fatty acids are attached via thioester linkages. To identify the Cys residue involved in the thioester linkages, 14C-carboxyamidomethylated RHL subunits were separated by SDS-polyacrylamide gel electrophoresis and digested in-gel with trypsin, and the resulting peptides were separated by reverse-phase high performance liquid chromatography. Amino acid sequence of radioactive peptides revealed that Cys35 in RHL1 and Cys54 in RHL2 and RHL3 were radiolabeled and, therefore, are fatty acylation sites. Fatty acylation of HHL subunits was analyzed by site-directed mutagenesis. Metabolic labeling of Cos7 cells transfected with wild type HHL1 cDNA resulted in substantial incorporation of [3H]palmitate into purified HHL1. Incorporation of [3H]palmitate into a C36S mutant of HHL1 was negligible ( approximately 1%) compared with wild type. This result also shows that Cys57 within the transmembrane domain of HHL1 is not normally palmitoylated. We conclude that Cys35 in RHL1, Cys54 in RHL2 and RHL3, and Cys36 in HHL1 are fatty acylated. Cys57 in HHL1 and probably Cys56 in RHL1 are not palmitoylated.