Proinsulin C-peptide activates α-enolase: implications for C-peptide--cell membrane interaction.
Proinsulin C-peptide activates α-enolase: implications for C-peptide--cell membrane interaction.
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DOI：
10.1093/jb/mvs052
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发表时间：
2012-07
影响因子：
2.7
通讯作者：
Tatsuya Ishii;Keigo Fukano;K. Shimada;A. Kamikawa;Y. Okamatsu-Ogura;A. Terao;Toshihide Yoshida;M. Saito;K. Kimura
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文献类型：
--
作者：
Tatsuya Ishii;Keigo Fukano;K. Shimada;A. Kamikawa;Y. Okamatsu-Ogura;A. Terao;Toshihide Yoshida;M. Saito;K. Kimura
胰岛素原C肽对1型糖尿病的微血管并发症具有有益作用。然而，尚未阐明膜C肽受体的可能存在。本研究的目的是确定和表征膜蛋白的C肽结合。α-烯醇化酶与HL-60细胞表面蛋白化学交联后与C肽免疫共沉淀，并经质谱鉴定。重组α-烯醇化酶活性受C肽调节，2-磷酸甘油酸的K（m）显著降低，而不影响V（max）。当酶的C-末端碱性赖氨酸残基（K434）被中性丙氨酸或酸性谷氨酸取代时，C-肽对酶的调节作用被消除，而不是被碱性精氨酸取代。通过C-肽的酶调节用含有对应于全长C-肽的位置27（E27）的谷氨酸的C-肽片段再现。添加赖氨酸类似物的测定和A31细胞培养废除酶的调制和MAP激酶激活的C-肽，分别。结果表明，C肽通过其E27与α-烯醇化酶K434之间的特异性相互作用而激活α-烯醇化酶。由于α-烯醇化酶作为纤溶酶原的细胞表面受体发挥作用，因此可以想象它也可以作为体内C肽的受体。
Proinsulin C-peptide shows beneficial effects on microvascular complications of Type 1 diabetes. However, the possible occurrence of membrane C-peptide receptor(s) has not been elucidated. The aim of this study was to identify and characterize membrane proteins to which C-peptide binds. The enzyme α-enolase was co-immunoprecipitated with C-peptide after chemical cross-linking to HL-60 cell surface proteins and identified by mass spectrometry. Recombinant α-enolase activity was modulated by C-peptide, with a significant decrease in K(m) for 2-phosphoglycerate without affecting V(max). The enzyme modulation by C-peptide was abolished when C-terminal basic lysine residue (K434) of the enzyme was replaced by neutral alanine or acidic glutamate, but not with basic arginine. The enzyme modulation by C-peptide was reproduced with the C-peptide fragments containing glutamate corresponding to position 27 (E27) of the full-length C-peptide. Addition of a lysine analogue to the assay and A31 cell culture abrogated the enzyme modulation and MAP kinase activation by C-peptide, respectively. The results indicate that C-peptide has the capacity to activate α-enolase through a specific interaction between E27 of the peptide and K434 of the enzyme. Since α-enolase plays a role as a cell surface receptor for plasminogen, it may conceivably also serve as a receptor for C-peptide in vivo.