SIMILARITY OF THE 3-DIMENSIONAL STRUCTURES OF ACTIN AND THE ATPASE FRAGMENT OF A 70-KDA HEAT-SHOCK COGNATE PROTEIN
SIMILARITY OF THE 3-DIMENSIONAL STRUCTURES OF ACTIN AND THE ATPASE FRAGMENT OF A 70-KDA HEAT-SHOCK COGNATE PROTEIN
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DOI：
10.1073/pnas.88.11.5041
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发表时间：
1991-06-01
影响因子：
11.1
通讯作者：
HOLMES, KC
中科院分区：
文献类型：
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作者：
FLAHERTY, KM;MCKAY, DB;HOLMES, KC
虽然这两种蛋白质之间的序列一致性很小，但兔骨骼肌肌动蛋白（375个氨基酸残基）和牛70 kDa热休克同源蛋白（HSC 70; 386个残基）的44 kDa ATP酶片段的结构非常相似。在两种蛋白质中结构等同的241对氨基酸残基的α-碳位置可以以2.3埃的距离的均方根差叠加;其中，39个残基是相同的，56个是保守取代。此外，ADP在两种蛋白质中的构象非常相似。一个局部序列的“指纹”，这可能是诊断的腺嘌呤核苷酸β-磷酸结合口袋，已经得到。指纹识别的甘油激酶家族的成员作为候选人可能具有类似的结构，在其核苷酸结合域。这两种分子之间的结构差异主要发生在肌动蛋白的环状区域，已知这些区域与肌动蛋白丝中的其他单体相互作用或与肌球蛋白结合;热休克蛋白中的相应区域可能具有尚未确定的功能。将肌动蛋白的Ca 2 + ATP置于ATP酶片段结构上表明Asp-206（对应于肌动蛋白的His-161）是ATP酶反应的候选质子受体。
Although there is very little sequence identity between the two proteins, the structures of rabbit skeletal muscle actin (375-amino acid residues) and the 44-kDa ATPase fragment of the bovine 70-kDa heat shock cognate protein (HSC70; 386 residues) are very similar. The alpha-carbon positions of 241 pairs of amino acid residues that are structurally equivalent within the two proteins can be superimposed with a root-mean-square difference in distance of 2.3 angstrom; of these, 39 residues are identical, and 56 are conservative substitutions. In addition, the conformations of ADP are very similar in both proteins. A local sequence "fingerprint," which may be diagnostic of the adenine nucleotide beta-phosphate-binding pocket, has been derived. The fingerprint identifies members of the glycerol kinase family as candidates likely to have a similar structure in their nucleotide-binding domains. The structural differences between the two molecules mainly occur in loop regions of actin known to be involved in interactions with other monomers in the actin filament or in the binding of myosin; the corresponding regions in heat shock proteins may have functions that are as yet undetermined. Placing the Ca2+ ATP of actin on the ATPase fragment structure suggests Asp-206 (corresponding to His-161 of actin) as a candidate proton acceptor for the ATPase reaction.