A major G protein alpha O isoform in bovine brain is deamidated at Asn346 and Asn347, residues involved in receptor coupling.
A major G protein alpha O isoform in bovine brain is deamidated at Asn346 and Asn347, residues involved in receptor coupling.
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牛脑中主要的 G 蛋白 α O 同工型在 Asn346 和 Asn347（参与受体偶联的残基）处脱酰胺。
DOI：
10.1021/bi981642q
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Hildebrandt,JD
中科院分区：
文献类型：
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作者：
McIntire,WE;Schey,KL;Knapp,DR;Hildebrandt,JD
异三聚体G蛋白go2的α亚基的两种主要形式之间的结构差异被发现是由于蛋白质c端附近的两个Asn残基中的任何一个在参与受体识别的区域中脱酰胺。go1是哺乳动物大脑中含量最多的异三聚体G蛋白。已知两种形式的蛋白goa和GOB是由单个GOα基因的选择性剪接产生的。第三种同工异构体αOC约占大脑α o蛋白的1/3，与αOA相关，被认为是由蛋白质修饰产生的。用质谱法和化学衍生法分析了α oa和α oca α -末端肽的结构差异。离子阱质谱法和Edman降解法对c端凝乳色氨酸片段进行了序列分析，鉴定出αOAas在αOC中的替代脱酰胺位点Asn346和Asn347。这些结构差异对G蛋白的功能有直接的影响，因为它们发生在参与受体识别和激活的蛋白质构象敏感部分。由于Asn347是αsfamily外大多数G蛋白α亚基中存在的保守残基，因此这些观察结果可能对许多G蛋白具有普遍意义。脱酰胺可能是修饰或适应由G蛋白介导的细胞反应的新过程的一个组成部分。
The structural differences between two major forms of the α subunit of the heterotrimeric G protein GOwere found to be due to deamidation of either of two Asn residues near the C-terminus of the proteins, in a region involved in receptor recognition. GOis the most abundant heterotrimeric G protein in mammalian brain. Two forms of the protein, GOAand GOB, are known to be generated by alternative splicing of a single GOα gene. A third isoform, αOC, represents about1/3of the αOprotein in brain and is related to αOA, from which it is thought to be generated by protein modification. Mass spectrometry and chemical derivatization of tryptic fragments of the proteins were used to localize the structural difference between αOAand αOCto a C-terminal peptide. Sequence analysis of a C-terminal chymotryptic fragment both by ion trap mass spectrometry and by Edman degradation identified Asn346 and Asn347 of αOAas alternative deamidation sites in αOC. These structural differences have immediate implications for G protein function, as they occur in a conformationally sensitive part of the protein involved in receptor recognition and activation. Since Asn347 is a conserved residue present in most G protein α subunits outside the αsfamily, these observations may have general significance for many G proteins. Deamidation may be a component of a novel process for modifying or adapting cellular responses mediated by G proteins.