Hayes J D, Strange R C, Percy-Robb I W
Biochem J. 1981 Aug 1;197(2):491-502. doi: 10.1042/bj1970491.
The two dimeric lithocholic acid-binding proteins previously identified as ligandin (YaYa) and glutathione S-transferase B (YaYc) were isolated from rat liver cytosol. These proteins have molecular weights of 44000 and 47000 respectively. The recovery of these two proteins from liver was not affected by the addition of the proteinase inhibitor Trasylol. No spontaneous interconversion between these two proteins was observed on storage. YaYa and YaYc proteins yielded peptides of identical molecular weight after limited digestion with Staphylococcus aureus V8 proteinase. Analytical and preparative tryptic-digest peptide 'maps' showed that all the soluble peptides obtained from YaYa protein were also recovered from YaYc protein. Approximately six extra soluble peptides, which were not recovered from YaYa protein, were obtained from the tryptic digest of YaYc protein. Subdigests of the insoluble tryptic-digest 'cores' also resulted in the recovery of identical peptides from both proteins. Evidence is presented that the Ya subunit possessed by both proteins is identical; glutathione S transferase B is a hybrid of ligandin and glutathione S-transferase AA. The Ya monomer is responsible for lithocholate binding.
先前鉴定为配体蛋白（YaYa）和谷胱甘肽S-转移酶B（YaYc）的两种二聚体石胆酸结合蛋白从大鼠肝脏胞质溶胶中分离得到。这些蛋白质的分子量分别为44000和47000。从肝脏中回收这两种蛋白质不受蛋白酶抑制剂抑肽酶添加的影响。储存时未观察到这两种蛋白质之间的自发相互转化。用金黄色葡萄球菌V8蛋白酶进行有限消化后，YaYa和YaYc蛋白产生分子量相同的肽段。分析性和制备性胰蛋白酶消化肽“图谱”表明，从YaYa蛋白获得的所有可溶性肽段也能从YaYc蛋白中回收。从YaYc蛋白的胰蛋白酶消化物中获得了大约六种额外的可溶性肽段，这些肽段不能从YaYa蛋白中回收。不溶性胰蛋白酶消化“核心”的亚消化物也导致从两种蛋白质中回收相同的肽段。有证据表明两种蛋白质所具有的Ya亚基是相同的；谷胱甘肽S-转移酶B是配体蛋白和谷胱甘肽S-转移酶AA的杂合体。Ya单体负责石胆酸盐的结合。
