Human low-Mr kininogen contains three copies of a cystatin sequence that are divergent in structure and in inhibitory activity for cysteine proteinases.
Author
Summary, in English
We point out that human low-Mr kininogen contains three cystatin-like sequences, rather than two, as had previously been thought. The protein was purified by affinity chromatography on carboxymethyl-papain-Sepharose, and subjected to limited proteolysis by trypsin and chymotrypsin. Fragments were isolated, and three corresponding to the individual cystatin-like domains were identified. By comparison with the known amino acid sequence of the protein they were numbered 1 to 3 from the N-terminus. Domain 1 was not found to have any inhibitory activity for cysteine proteinases, which is consistent with the absence of residues that are highly conserved in inhibitors of the cystatin superfamily, and have previously been suggested to be essential for activity. Domain 2 was a good inhibitor of chicken calpain, and also papain and cathepsin L. Domain 3 showed negligible inhibition of calpain, but inhibited papain and cathepsin L strongly. The probable arrangement of disulphide bonds in the heavy chain of low-Mr kininogen is deduced from the homology with the cystatins and other evidence contained in the present paper.
Department/s
Publishing year
1986
Language
English
Pages
429-434
Publication/Series
Biochemical Journal
Volume
234
Issue
2
Links
Document type
Journal article
Publisher
Portland Press
Topic
- Biochemistry and Molecular Biology
Status
Published
ISBN/ISSN/Other
- ISSN: 0264-6021