Identification and characterization of novel isoforms of COPI subunits
Identification and characterization of novel isoforms of COPI subunits
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DOI：
10.1093/oxfordjournals.jbchem.a022817
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发表时间：
2000-11-01
影响因子：
2.7
通讯作者：
Nakayama, K
中科院分区：
文献类型：
--
作者：
Futatsumori, M;Kasai, K;Nakayama, K
CoP I包被的囊泡参与早期分泌途径中的囊泡运输。CoP-1涂层由7个亚基组成，即α-、β-、β‘-、伽马-、三角洲-、epsilon-和Zeta-CoPS。然而，有证据表明可能存在COP I亚单位的异构体，在本研究中，我们确定了Gamma-COP(Gamma2-COP；本文将原始Gamma-COP称为Gamma1-COP)和Zeta-COP(zeta2-COP；原始Zeta-COP称为zeta1-COP)的同系物。Gamma1-和Gamma2-COPS和zeta1-和zeta2-COPS分别分享80%和75%的氨基酸。Gamma2-COP和zeta2-COP的mRNAs普遍表达，提示它们在细胞功能中发挥重要作用。免疫荧光分析表明，Gamma2-COP和zeta2-COP与β-COP共定位于核旁顺式高尔基体区域。酵母双杂交分析表明，Gamma1-和Gamma2-COPS可以直接与zeta1-和zeta2-COPS相互作用，尽管是混杂的。与Gamma1-CoP、Gamma2-CoP在体内可与β-CoP形成复合体一样，含Gamma1-CoP和含Gamma2-CoP的复合体也能与p23的胞浆结构域发生类似的相互作用。这些结果表明，Gamma2-CoP和zeta2-CoP可以分别代替Gamma1-CoP和zeta1-CoP形成类CoP复合体，提示CoP I复合体和类CoP复合体在功能上是多余的。
COP I-coated vesicles are involved in vesicular trafficking in the early secretory pathway. The COP I coat is composed of seven subunits, alpha-, beta-, beta'-, gamma-, delta-, epsilon-, and zeta -COPs. Evidence suggests, however, that there may be isoforms of the COP I subunits, In the present study, we identified homologs of gamma -COP (gamma2-COP; original gamma -COP is referred to as gamma1-COP in this paper) and of zeta -COP (zeta2-COP; original zeta -COP is referred to as zeta1-COP). gamma1-and gamma2-COPs, and zeta1- and zeta2-COPs share 80 and 75%, respectively, of amino acids. mRNAs for gamma2-COP and zeta2-COP are expressed ubiquitously, suggesting their fundamental role in cellular function. Immunofluorescence analysis shows that gamma2-COP and zeta2-COP are colocalized with beta -COP in the paranuclear cis-Golgi region. Yeast two-hybrid analysis indicates that gamma1- and gamma2-COPs can directly, albeit promiscuously, interact with zeta1- and zeta2-COPs. Like gamma1-COP, gamma2-COP can, form a complex with beta -COP in vivo, The gamma1-COP-containing and gamma2-COP-containing complexes can similarly interact with the cytoplasmic domain of p23, These results indicate that gamma2-COP and zeta2-COP can form a COP I-like complex in place of gamma1-COP and zeta1-COP, respectively, and suggest that the COP I complex and the COP I-like complex are functionally redundant.