Isolation and the complete amino acid sequence of lumenal endoplasmic reticulum glucose-6-phosphate dehydrogenase.
Isolation and the complete amino acid sequence of lumenal endoplasmic reticulum glucose-6-phosphate dehydrogenase.
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腔内质网葡萄糖-6-磷酸脱氢酶的分离和完整氨基酸序列。
DOI：
10.1073/pnas.90.11.5302
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发表时间：
1993
影响因子：
11.1
通讯作者：
Ozols,J
中科院分区：
文献类型：
--
作者：
Ozols,J
我从兔肝微粒体中分离出葡萄糖-6-磷酸脱氢酶，并测定了其完整的氨基酸序列。序列测定是通过化学和酶裂解产生的肽的自动Edman降解来实现的。微粒体酶由763个残基组成，与先前表征的细胞质酶完全不同。微粒体酶的N端被焦谷氨酰残基阻断。碳水化合物附着在Asn-138和Asn-263上，这意味着大部分蛋白质定向在内质膜的管腔一侧。微粒体蛋白的氨基酸序列与广泛测序的细胞质葡萄糖-6-磷酸脱氢酶具有有限的同源性。最多六个相同残基的簇可以在四个区域被识别：残基10-21、154-163和173-261的肽段。此外，另一组相同的残基，需要在微粒体酶序列中删除100个残基，横跨残基436-462，对应于胞质蛋白的残基348-373。在Gly-399和Gly-491位点鉴定出两个与辅酶结合褶相关的gly - xaa - xaa - gly基序片段。在胞质酶中，该序列基序的变异发生在Gly-37和Gly-241。微粒体酶的300个残基c端段是独特的，在细胞质酶或细菌酶中没有对应的酶。关于微体酶的一个意想不到的发现是，它缺乏可识别的膜跨越区域或管状蛋白c端一致序列Lys-Asp-Glu或His-Ile/Thr-Glu-Leu。因此，该蛋白在内质网管腔内的转运和滞留方式仍有待确定。
I have isolated glucose-6-phosphate dehydrogenase from rabbit liver microsomes and determined its complete amino acid sequence. Sequence determination was achieved by automated Edman degradation of peptides generated by chemical and enzymatic cleavages. The microsomal enzyme consists of 763 residues and is quite dissimilar from the previously characterized cytosolic enzymes. The N terminus of the microsomal enzyme is blocked by a pyroglutamyl residue. Carbohydrate is attached at Asn-138 and Asn-263, implying that the bulk of the protein is oriented on the lumenal side of the endoplasmic membrane. The amino acid sequence of the microsomal protein shows limited homology to the extensively sequenced cytosolic glucose-6-phosphate dehydrogenases. Clusters of up to six identical residues can be identified in four regions: peptide segments at residues 10-21, 154-163, and 173-261. In addition, another array of identical residues, requiring a 100-residue deletion in the sequence of the microsomal enzyme, spans residues 436-462 and corresponds to residues 348-373 of the cytosolic protein. Two segments with a Gly-Xaa-Gly-Xaa-Xaa-Gly motif, related to a coenzyme binding fold, were identified at Gly-399 and Gly-491. In the cytosolic enzymes, a variation of this sequence motif occurs at Gly-37 and Gly-241. The 300-residue C-terminal segment of the microsomal enzyme is unique and has no counterpart in the cytosolic or the bacterial enzymes. An unexpected finding with regard to the microsomal enzyme is that it lacks an identifiable membrane-spanning region or the lumenal-protein C-terminal consensus sequences Lys-Asp-Glu or His-Ile/Thr-Glu-Leu. Thus, the mode of transport and retention of this protein in the lumen of endoplasmic reticulum remains to be determined.