Ogrinc T, Dolenc I, Ritonja A, Turk V
Department of Biochemistry and Molecular Biology, Jozef Stefan Institute, Ljubljana, Slovenia.
FEBS Lett. 1993 Dec 28;336(3):555-9. doi: 10.1016/0014-5793(93)80875-u.
The complex of cathepsin L and the fragment of the MHC class II-associated invariant chain was purified from human kidney. M(r) of the complex, as determined by gel filtration, is about 40,000. Both components were identified by amino acid and sequence analyses. The bound invariant chain fragment is almost identical to the additional segment found in p41, but not in the p31 form of the invariant chain. The complex has significantly enhanced stability at neutral and slightly alkaline pH, and reduced proteolytic activity against the synthetic substrate Z-Phe-Arg-MCA compared to free cathepsin L. The complex exhibits no enzymatic activity against the protein substrate azocasein. For the first time, the invariant chain was found in a complex with a protein, which was not an MHC molecule.
组织蛋白酶L与MHC II类相关恒定链片段的复合物是从人肾脏中纯化得到的。通过凝胶过滤测定，该复合物的相对分子质量约为40,000。通过氨基酸和序列分析鉴定了两种组分。结合的恒定链片段与在p41中发现的额外片段几乎相同，但在恒定链的p31形式中不存在。与游离的组织蛋白酶L相比，该复合物在中性和微碱性pH下具有显著增强的稳定性，并且对合成底物Z-苯丙氨酸-精氨酸-甲基香豆素酰胺的蛋白水解活性降低。该复合物对蛋白质底物偶氮酪蛋白没有酶活性。首次发现恒定链与一种非MHC分子的蛋白质形成复合物。
