Golgi-specific DHHC Zinc Finger Protein GODZ Mediates Membrane Ca2+ Transport
Golgi-specific DHHC Zinc Finger Protein GODZ Mediates Membrane Ca2+ Transport
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DOI：
10.1074/jbc.m109.069849
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发表时间：
2010-02-12
影响因子：
4.8
通讯作者：
Quamme, Gary A.
中科院分区：
文献类型：
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作者：
Hines, Rochelle M.;Kang, Rujun;Quamme, Gary A.
高尔基体特异性锌指蛋白GODZ（棕榈酰酰基转移酶/DHHC-3）介导调节膜-蛋白相互作用的许多蛋白质底物的棕榈酰化和翻译后修饰。在这里，我们表明，GODZ也介导表达非洲爪蟾卵母细胞中的Ca 2+运输。双电极电压钳、荧光和Ca-45（2+）同位素摄取测定表明，在表达GODZ cRNA的卵母细胞中存在电压和浓度依赖性、可饱和性和底物可降解性的Ca 2+转运，但在单独注射水的卵母细胞中不存在。此外，我们表明，GODZ介导的Ca 2+转运调节棕榈酰化，棕榈酰酰基转移酶抑制剂2-溴棕榈酸酯或改变的酰基转移酶DHHC基序（GODZ-DHHS）减少GODZ介导的Ca 2+转运相似的80%。GODZ突变V61 R取消钙离子转运，但不影响棕榈酰酰基转移酶活性。GODZ-V61 R与GODZ-DHHS的共表达使GODZ-DHHS介导的Ca 2+摄取恢复到野生型GODZ所观察到的值，排除棕榈酰化的内源性效应。一个独立的棕榈酰基转移酶（HIP 14）与GODZ-DHHS突变体的共表达也挽救了Ca 2+转运。HIP 14单独表达时不介导Ca 2+转运。免疫细胞化学研究表明，GODZ和HIP 14共定位于高尔基体和相同的后高尔基体囊泡，这表明异棕榈酰化可能发挥生理作用，除了生化功能。我们的结论是，GODZ编码的钙离子转运蛋白除了其棕榈酰化蛋白质底物的能力。
The Golgi-specific zinc finger protein GODZ (palmitoyl acyltransferase/DHHC-3) mediates the palmitoylation and post-translational modification of many protein substrates that regulate membrane-protein interactions. Here, we show that GODZ also mediates Ca2+ transport in expressing Xenopus laevis oocytes. Two-electrode voltage-clamp, fluorescence, and Ca-45(2+) isotopic uptake determinations demonstrated voltage-and concentration-dependent, saturable, and substrate-inhibitable Ca2+ transport in oocytes expressing GODZ cRNA but not in oocytes injected with water alone. Moreover, we show that GODZ-mediated Ca2+ transport is regulated by palmitoylation, as the palmitoyl acyltransferase inhibitor 2-bromopalmitate or alteration of the acyltransferase DHHC motif (GODZ-DHHS) diminished GODZ-mediated Ca2+ transport by similar to 80%. The GODZ mutation V61R abolished Ca2+ transport but did not affect palmitoyl acyltransferase activity. Coexpression of GODZ-V61R with GODZ-DHHS restored GODZ-DHHS-mediated Ca2+ uptake to values observed with wild-type GODZ, excluding an endogenous effect of palmitoylation. Coexpression of an independent palmitoyl acyltransferase (HIP14) with the GODZ-DHHS mutant also rescued Ca2+ transport. HIP14 did not mediate Ca2+ transport when expressed alone. Immunocytochemistry studies showed that GODZ and HIP14 co-localized to the Golgi and the same post-Golgi vesicles, suggesting that heteropalmitoylation might play a physiological role in addition to a biochemical function. We conclude that GODZ encodes a Ca2+ transport protein in addition to its ability to palmitoylate protein substrates.