Proteinase inhibitor I25, cystatin | |||||||||
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Crystal structure of an immunomodulatory salivary cystatin from the soft tick Ornithodoros moubata from PDB entry 3L0R.
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Identifiers | |||||||||
Symbol | Prot_inh_cystat | ||||||||
Pfam | PF00031 | ||||||||
Pfam clan | CL0121 | ||||||||
InterPro | IPR000010 | ||||||||
SMART | SM00043 | ||||||||
PROSITE | PDOC00259 | ||||||||
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Available protein structures: | |
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Pfam | structures |
PDB | RCSB PDB; PDBe; PDBj |
PDBsum | structure summary |
The cystatins are a family of cysteine protease inhibitors which share a sequence homology and a common tertiary structure of an alpha helix lying on top of an anti-parallel beta sheet. The family is subdivided as described below.
Cystatins show similarity to fetuins, kininogens, histidine-rich glycoproteins and cystatin-related proteins. Cystatins mainly inhibit peptidase enzymes (another term for proteases) belonging to peptidase families C1 (papain family) and C13 (legumain family). They are known to mis-fold to form amyloid deposits and are implicated in several diseases.
The cystatin family includes:
van Wyk et al found some 19 different cystatins similar to oryzacystatin-I in the soybean along with related cysteine proteases.
Chicken cystatin quickly passed the membrane of MCF-10A neo T cells and inhibited cathepsin B when it was acylated with fatty acyl residues of 6-18 carbon atoms.
This article incorporates text from the public domain Pfam and InterPro IPR000010