C-peptide binding to human cell membranes:: Importance of Glu27
C-peptide binding to human cell membranes:: Importance of Glu27
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DOI：
10.1006/bbrc.2001.4917
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发表时间：
2001-06-01
影响因子：
3.1
通讯作者：
Johnansson, J
中科院分区：
文献类型：
--
作者：
Pramanik, A;Ekberg, K;Johnansson, J
除了其在胰岛素原折叠中的既定作用外，C肽还具有调节细胞活性的功能。这种31个残基的肽影响胰岛素依赖型糖尿病患者的肾脏、血管和代谢功能。已证明C肽与细胞的结合，C肽可被其C末端五肽取代。我们现在已经使用荧光相关光谱法来研究C肽结合的五肽部分的结构要求。将所有五肽残基E（27）GSLQ（31）分别替换为Ala，并测定所得肽从人肾小管细胞膜置换罗丹明标记的全长人C肽的能力。这表明Glu 27对于置换是必不可少的，而用Ala置换Gly 28几乎没有影响，并且置换三个最C末端残基中的任何一个具有中等影响。此外，游离Glu置换全长C肽约50%，而游离Ala、C肽（1-26）和截短的五肽（对应于四肽G（28）SLG（31））没有置换能力。肽EVARQ（对应于大鼠C末端五肽）和ELGGGPGAG（对应于人C肽的位置11-19）不置换人C肽。这些结果表明C肽的Glu 27在与细胞靶点的结合中起关键作用。
In addition to its established role in proinsulin folding, C-peptide has a function in regulation of cellular activity. The 31-residue peptide influences renal, vascular, and metabolic functions in patients with insulin-dependent diabetes mellitus. Binding to cells has been demonstrated for C-peptide, which can be displaced by its C-terminal pentapeptide. We have now used fluorescence correlation spectroscopy to investigate structural requirements on the pentapeptide part for C-peptide binding. All pentapeptide residues, E(27)GSLQ(31), were individually replaced with Ala and the capacity of the resulting peptides to displace rhodamine-labelled full-length human C-peptide from human renal tubular cell membranes was determined. This showed that Glu27 is essential for displacement, while replacement of Gly28 with Ala has little effect, and replacement of any of the three most C-terminal residues had intermediate effects. Moreover, free Glu displaces full-length C-peptide to about 50%, while free Ala, C-peptide(1-26), and the truncated pentapeptide, corresponding to the tetrapeptide G(28)SLG(31), have no displacing capacity. The peptides EVARQ (corresponding to the rat C-terminal pentapeptide) and ELGGGPGAG (corresponding to positions 11-19 of human C-peptide) do not displace human C-peptide. These results indicate that Glu27 of C-peptide is critically involved in binding to cellular targets, a zool Academic Press.