Identification of the pH-dependent membrane anchor of carboxypeptidase E (EC 3.4.17.10).
Identification of the pH-dependent membrane anchor of carboxypeptidase E (EC 3.4.17.10).
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DOI：
10.1016/s0021-9258(19)39824-2
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发表时间：
1990-02
期刊：
影响因子：
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通讯作者：
L. Fricker;B. Das;R. Angeletti
中科院分区：
文献类型：
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作者：
L. Fricker;B. Das;R. Angeletti
羧肽酶E（CPE），肽酶加工酶，存在于分泌颗粒中的可溶性形式和形式，这是膜结合在pH 5.5，但可溶于中性pH值。抗血清提出了对肽对应于预测的COOH-末端的CPE结合到膜相关形式的CPE，但不可溶的形式。预计该COOH末端区域形成两亲性α-螺旋，含有由亲水残基分离的几对疏水残基。长度为11-24个残基的合成COOH-末端肽能够与牛垂体膜结合，并且可以通过提取膜结合形式的CPE的条件进行提取。pH值对21-残基COOH-末端肽的膜结合的影响类似于CPE的膜结合：在pH值小于6时，大部分肽是膜结合的，而在pH值大于8时，小于20%是膜结合的。21-残基COOH-末端肽和纯化的膜形式的CPE，但不是可溶性形式，分区到Triton X-114仅在低pH值（pH值小于6）。COOH-末端肽的极性和疏水相互作用似乎是CPE与膜的可逆的，pH依赖性协会负责。
Carboxypeptidase E (CPE), a peptide hormone-processing enzyme, is present within secretory granules in both a soluble form and a form which is membrane-bound at pH 5.5 but soluble at neutral pH. Antisera raised against a peptide corresponding to the predicted COOH-terminus of CPE bind to the membrane-associated form of CPE but not to the soluble form. This COOH-terminal region is predicted to form an amphiphilic alpha-helix, containing several pairs of hydrophobic residues separated by hydrophilic residues. Synthetic COOH-terminal peptides 11-24 residues in length are able to bind to bovine pituitary membranes and can be extracted by conditions that extract the membrane-bound form of CPE. The influence of pH on the membrane binding of a 21-residue COOH-terminal peptide is similar to the membrane binding of CPE: at pH values less than 6 the majority of the peptide is membrane-bound, while at pH values above 8 less than 20% is membrane-bound. Both the 21-residue COOH-terminal peptide and the purified membrane form of CPE, but not the soluble form, partition into Triton X-114 only at low pH (pH less than 6). Combined polar and hydrophobic interactions of the COOH-terminal peptide appear to be responsible for the reversible, pH-dependent association of CPE with membranes.