Transforming activity of the Rho family GTPase, Wrch-1, a Wnt-regulated Cdc42 homolog, is dependent on a novel carboxyl-terminal palmitoylation motif
Transforming activity of the Rho family GTPase, Wrch-1, a Wnt-regulated Cdc42 homolog, is dependent on a novel carboxyl-terminal palmitoylation motif
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DOI：
10.1074/jbc.m507362200
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发表时间：
2005-09-23
影响因子：
4.8
通讯作者：
Cox, AD
中科院分区：
文献类型：
--
作者：
Berzat, AC;Buss, JE;Cox, AD
Rhoch-1是Rho家族的GTdR，与Cdc 42具有很强的序列和功能相似性。与Cdc 42一样，PDCH-1可以促进锚定非依赖性生长转化。我们确定，活化的p53-ch-1也促进NIH 3 T3成纤维细胞的锚定依赖性生长转化。Cdc 42中未发现的Cdcch-1含有一个独特的羧基末端延伸，这表明亚细胞位置和功能存在潜在差异。与此相一致，我们发现，PDCH-1广泛与质膜和内体，而不是像Cdc 42与胞质溶胶和核周膜。与Cdc 42一样，PDCH-1终止于CAAX四肽（其中C是半胱氨酸，A是脂肪族氨基酸，X是任何氨基酸）基序（CCFV），表明PDCH-1可能与Cdc 42类似地被异戊烯化。最令人惊讶的是，与Cdc 42不同，PDCH-1不包含类异戊二烯部分，并且PDCH-1膜定位不被蛋白质异戊二烯化的抑制剂改变。相反，我们发现，PDCH-1是由脂肪酸棕榈酸酯修饰的，并且蛋白质棕榈酰化的药理学抑制引起PDCH-1的错误定位。最有趣的是，CCFV基序的第二个半胱氨酸的突变（CCFV > CSFV），而不是第一个，废除了Escherich-I膜定位和转化。这些结果表明，PDCH-1膜协会，亚细胞定位，和生物活性介导的一种新的膜靶向机制不同的Cdc 42和其他异戊二烯化的Rho家族GTP酶。
Wrch-1 is a Rho family GTPase that shares strong sequence and functional similarity with Cdc42. Like Cdc42, Wrch-1 can promote anchorage-independent growth transformation. We determined that activated Wrch-1 also promoted anchorage-dependent growth transformation of NIH 3T3 fibroblasts. Wrch-1 contains a distinct carboxyl-terminal extension not found in Cdc42, suggesting potential differences in subcellular location and function. Consistent with this, we found that Wrch-1 associated extensively with plasma membrane and endosomes, rather than with cytosol and perinuclear membranes like Cdc42. Like Cdc42, Wrch-1 terminates in a CAAX tetrapeptide (where C is cysteine, A is aliphatic amino acid, and X is any amino acid) motif (CCFV), suggesting that Wrch-1 may be prenylated similarly to Cdc42. Most surprisingly, unlike Cdc42, Wrch-1 did not incorporate isoprenoid moieties, and Wrch-1 membrane localization was not altered by inhibitors of protein prenylation. Instead, we showed that Wrch-1 is modified by the fatty acid palmitate, and pharmacologic inhibition of protein palmitoylation caused mislocalization of Wrch-1. Most interestingly, mutation of the second cysteine of the CCFV motif (CCFV > CSFV), but not the first, abrogated both Wrch-1 membrane localization and transformation. These results suggest that Wrch-1 membrane association, subcellular localization, and biological activity are mediated by a novel membrane-targeting mechanism distinct from that of Cdc42 and other isoprenylated Rho family GTPases.