| Autor: |
Katunuma, Nobuhiko, Kakegawa, Hisao, Matsunaga, Youichi, Saibara, Toshiji |
| Zdroj: |
FEBS Letters; January 1994, Vol. 349 Issue: 2 p265-269, 5p |
| Abstrakt: |
The primary structure of p31 of invariant chain (Ii-chain) shows about 50% homology with those of the cystatin family which are endogenous cysteine protease inhibitors. The binding domains between Ii-chain and HLA-DR-7 were estimated from the structural homology between cystatin and Ii-chain and also between cathepsins and DR-7, respectively. The QL 64–71and GS 76–88of Ii-Chain were estimated to be the binding domains with GG 45–51, and VS 57–63of HLA-DR7, respectively. The purified human Ii-chain from spleen is capable of forming four molecular forms from monomer to tetramer by redox-potential dependent disulfide bond formation. The Ii-chain inhibits cathepsin L and H competitively as a dimer and the Ki value for cathepsin L was 4.1 × 10 −8M, but cathepsin B was not inhibited at all. The Ii-chain showed mainly a dimer (60 kDa) under the assay condition of cathepsins with cysteine and was not degraded by these cathepsins. The Ii-chain may play an important role in the regulation of antigenic peptide presentation to MHC class II. |
| Databáze: |
Supplemental Index |
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