IDENTIFICATION OF DIPEPTIDYL PEPTIDASE-IV AS A PROTEIN SHARED BY THE PLASMA-MEMBRANE OF HEPATOCYTES AND LIVER BIOMATRIX
IDENTIFICATION OF DIPEPTIDYL PEPTIDASE-IV AS A PROTEIN SHARED BY THE PLASMA-MEMBRANE OF HEPATOCYTES AND LIVER BIOMATRIX
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DOI：
10.1016/0014-4827(85)90474-4
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发表时间：
1985-01-01
影响因子：
3.7
通讯作者：
HIXSON, DC
中科院分区：
文献类型：
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作者：
WALBORG, EF;TSUCHIDA, S;HIXSON, DC
肝实质的组织类型包括肝细胞与支持生物基质的特异性细胞间接触和相互作用。鉴定出一种由大鼠肝细胞质膜和大鼠肝生物基质共同组成的多肽(Hep105，表观分子量105,000)。经鉴定，Hep105为二肽基肽酶IV(DPPIV；EC 3.4.14.-)的多肽成分。用单抗(MAb 236.3)从表面标记的125I肝细胞的非离子洗涤剂提取物中免疫沉淀DPPIV。免疫沉淀物包括两个~(125)I标记的多肽：Hep105和一个表观分子量为150,000的多肽(Hep150)。金黄色葡萄球菌V8酶对~(125)I标记的Hep105和Hep150的蛋白降解产物基本相同，表明它们在结构上具有亲缘关系。只有Hep150在转印迹分析中显示出DPPIV活性，这与它是该酶的单体形式的解释是一致的。采暖(100度。在十二烷基硫酸钠(十二烷基硫酸钠)存在下，纯化的Hep150在C，5min内转化为Hep105，并且任何可显示的酶活性消失。~3H标记的二异丙基氟磷酸盐被掺入到Hep105中，表明其含有DPPIV的活性部位。纯化的大鼠肝脏生物基质具有显著的DPPIV活性。显然，Hep105是DPPIV的一个多肽成分。
Th histotypic organization of liver parenchyma involves specific intercellular contacts and interaction of hepatocytes with supporting biomatrix. A peptide (Hep105, apparent MW 105,000) was identified that is shared by the plasma membrane of rat hepatocytes and rat liver biomatrix. Hep105 was identified as a peptide component of dipeptidyl peptidase IV (DPPIV; EC 3.4.14.-). A monoclonal antibody (MAb 236.3) immunoprecipitated DPPIV from non-ionic detergent extracts of surface-labeled 125I hepatocytes. The immunoprecipitate comtained two 125I-labeled peptides: Hep105 and a peptide of apparent MW 150,000 (Hep150). Proteolysis of 125I-labeled Hep105 and Hep150 by Staphylococcus aureus V8 protease yielded essentially identical patterns of 125I-labeled peptide degradation products, indicating that Hep105 and Hep150 are structurally related. Only Hep150 exhibited DPPIV activity on transblot analysis, an observation that is consistent with the interpretation that it is the monomeric form of the enzyme. Heating (100.degree. C, 5 min) of purified Hep150 in the presence of sodium dodecylsulfate (SDS) resulted in its conversion to Hep105 and the disappearance of any demonstrable enzymatic activity. 3H-labeled diisopropyl fluorophosphate was incorporated into Hep105, indicating that Hep105 contains the active site for DPPIV. Purified rat liver biomatrix possessed significant DPPIV activity. Apparently, Hep105 is a peptide component of DPPIV.