Mammalian prenylcysteine carboxyl methyltransferase is in the endoplasmic reticulum
Mammalian prenylcysteine carboxyl methyltransferase is in the endoplasmic reticulum
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DOI：
10.1074/jbc.273.24.15030
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发表时间：
1998-06-12
影响因子：
4.8
通讯作者：
Philips, MR
中科院分区：
文献类型：
--
作者：
Dai, Q;Choy, E;Philips, MR
丙炔半胱氨酸羧甲基转移酶（pcCMT）是翻译后修饰c端CAAX基序的三种酶中的第三种，从而将CAAX蛋白靶向到质膜上。在这里，我们报告了第一个哺乳动物（人髓系）pcCMT的分子特征和亚细胞定位。推导出的哺乳动物pcCMT的氨基酸序列预测了一种与酵母pcCMT、STE14和哺乳动物3带阴离子转运蛋白同源的多膜跨越蛋白。人类基因补充了ste14突变体。pcCMT mrna在人体组织中普遍表达。抗pc- cmt抗血清在髓细胞膜中检测到33-kDa蛋白。异位表达的重组pc-CMT具有与中性粒细胞膜相同的酶活性。哺乳动物的pcCMT并不在质膜上表达，而是局限于内质网。因此，修饰CAAX基序的最后一个酶位于从拓扑结构上与CAAX蛋白靶膜分离的膜上。
Prenylcysteine carboxyl methyltransferase (pcCMT) is the third of three enzymes that posttranslationally modify C-terminal CAAX motifs and thereby target CAAX proteins to the plasma membrane. Here we report the molecular characterization and subcellular localization of the first mammalian (human myeloid) pcCMT. The deduced amino acid sequence of mammalian pcCMT predicts a multiple membrane-spanning protein with homologies to the yeast pcCMT, STE14, and the mammalian band 3 anion transporter. The human gene complemented a ste14 mutant. pcCMT mRNAs were ubiquitously expressed in human tissues. An anti-pc-CMT antiserum detected a 33-kDa protein in myeloid cell membranes. Ectopically expressed recombinant pc-CMT had enzymatic activity identical to that observed in neutrophil membranes. Mammalian pcCMT was not expressed at the plasma membrane but rather restricted to the endoplasmic reticulum. Thus, the final enzyme in the sequence that modifies CAAX motifs is located in membranes topologically removed from the CAAX protein target membrane.