Differential processing of guanylyl cyclase C along villus-crypt axis of rat small intestine.
Differential processing of guanylyl cyclase C along villus-crypt axis of rat small intestine.
复制标题
鸟苷酸环化酶 C 沿大鼠小肠绒毛-隐窝轴的差异加工。
DOI：
10.1152/ajpcell.1997.272.6.c1995
复制
发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Chong,KM
中科院分区：
文献类型：
--
作者：
Scheving,LA;Chong,KM
许多产肠毒素大肠杆菌菌株产生热稳定肽肠毒素（STa），其结合肠受体鸟苷酸环化酶C（GC-C）。STa受体在结构上是异质性的，但导致这种异质性的分子事件仍然不清楚。我们研究了细胞位置沿着绒毛-隐窝轴对ST a受体异质性的影响，通过分离在绒毛-隐窝方向分离的EDTA-解离细胞。STa亲和标记实验显示，最初释放的绒毛“尖端”级分具有四种主要的STa结合蛋白（STBP），其相对分子量（M（r））为150，000、135，000、125，000和95，000，其不与GC-C羧基末端抗体反应。然而，随后的绒毛细胞组分具有主要的免疫反应性STBP，M（r）为275，000和250，000。这些较大的GC-C同种型的有限蛋白水解产生1）较小的STBP，其具有与初始绒毛部分中的那些相似的M（r），2）不结合STa的65，000 M（r）蛋白GC-C同种型，和3）升高的基础和STa诱导的环化酶活性。我们的数据表明，STBP在完整的肠道结构的异质性，主要来自GC-C的多位点蛋白水解加工。
Many strains of enterotoxigenic Escherichia coli produce a heat-stable peptide enterotoxin (STa) that binds to the intestinal receptor guanylyl cyclase C (GC-C). STa receptors are structurally heterogeneous, but the molecular events causing this heterogeneity remain obscure. We examined the influence of cell position along the villus-crypt axis on STa receptor heterogeneity by fractionating EDTA-dissociated cells that detached in a villus-to-crypt direction. STa affinity labeling experiments revealed that the initially released villus “tip” fraction had four major STa binding proteins (STBPs), with relative molecular weight (M(r)) of 150,000, 135,000, 125,000, and 95,000, that did not react with a GC-C carboxy-terminal antibody. Yet succeeding villus cell fractions had major immunoreactive STBPs with M(r) of 275,000 and 250,000. Limited proteolysis of these larger GC-C isoforms produced 1) smaller STBPs that had M(r) similar to those in the initial villus fraction, 2) a 65,000 M(r) protein GC-C isoform that did not bind STa, and 3) elevated basal and STa-induced cyclase activity. Our data show that STBP structural heterogeneity in the intact intestine arises largely from multisite proteolytic processing of GC-C.