Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01034 (cystatin C)
 3,397 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human cystatins C and D share almost identical primary structures of two out of the three segments proposed to be of importance for enzyme interactions but have markedly different profiles for inhibition of the target cysteine peptidases, cathepsins B, H, L, and S. To investigate if the N-terminal binding regions of the inhibitors are responsible for the different inhibition profiles, and thereby confer biological selectivity, two hybrid cystatins were produced in Escherichia coli expression systems. In one hybrid, the N-terminal segment of cystatin C was placed on the framework of cystatin D, and the second was engineered with the N-terminal segment of cystatin D on the cystatin C scaffold. Truncated cystatin C and D variants, devoid of their N-terminal segments, were obtained by incubation with glycyl endopeptidase and isolated, in a second approach to assess the importance of the N-terminal binding regions for cystatin function and specificity. The affinities of the four cystatin variants for cathepsins B, H, L, and S were measured. By comparison with corresponding results for wild-type cystatins C and D, it was concluded (1) that both the N-terminal and framework part of the molecules significantly contribute to the observed differences in inhibitory activities of cystatins C and D and (2) that the N-terminal segment of cystatin C increases the inhibitory activity of cystatin D against cathepsin S and cathepsin L but results in decreased activity against cathepsin H. These differences in specificity were explained by the residues interacting with the S2 subsite of peptidases (Val- and Ala-10 in cystatin C and D, respectively). Also, removal of the N-terminal segment results in total loss of enzyme affinity for cystatin D but not for cystatin C. Therefore, structural differences in the framework parts, as well as in the N-terminal segments, are critical for both inhibitory specificity and potency. Homology modeling was used to identify residues likely responsible for the generally reduced inhibitory potency of cystatin D.
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PMID:Structural basis for different inhibitory specificities of human cystatins C and D. 952 28

Androgen insensitivity syndromes are due to defects in the androgen receptor gene. In this study, we analyzed the androgen receptor gene in four cases with complete androgen insensitivity syndrome. In patient 1, one substitutional mutation [arginine (codon CGC) to cysteine (codon TGC) at position 774] of exon F was identified. This position was located in the hormone binding domain and appeared to be one hot spot of mutations because the mutations at the same position in several unrelated cases were reported before. In patient 2, one substitutional mutation [tyrosine (codon TAT) to cysteine (codon TGT) at position 571] of exon B was identified. This position was located in the DNA binding domain. In patients 3 and 4 (siblings), one substitutional mutation [arginine (codon CGA) to glutamine (codon CAA) at position 752] of exon E was identified. Taken together, these abnormalities might be related to the pathogenesis of complete androgen insensitivity.
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PMID:Molecular analysis of the androgen receptor gene in 4 patients with complete androgen insensitivity. 954 75

The human squamous cell carcinoma antigens (SCCA) 1 and 2 are tandemly arrayed genes that encode two high-molecular-weight serine proteinase inhibitors (serpins). Although these proteins are 92% identical, differences in their reactive site loops suggest that they inhibit different types of proteinases. Our previous studies show that SCCA2 inhibits chymotrypsin-like serine proteinases [Schick et al. (1997) J. Biol. Chem. 272, 1849-1855]. We now show that, unlike SCCA2, SCCA1 lacks inhibitory activity against any of the more common types of serine proteinases but is a potent cross-class inhibitor of the archetypal lysosomal cysteine proteinases cathepsins K, L, and S. Kinetic analysis revealed that SCCA1 interacted with cathepsins K, L, and S at 1:1 stoichiometry and with second-order rate constants >/= 1 x 10(5) M-1 s-1. These rate constants were comparable to those obtained with the prototypical physiological cysteine proteinase inhibitor, cystatin C. Also relative to cystatin C, SCCA1 was a more potent inhibitor of cathepsin K-mediated elastolytic activity by forming longer lived inhibitor-proteinase complexes. The t1/2 of SCCA1-cathepsin S complexes was >1155 min, whereas that of cystatin C-cathepsin complexes was 55 min. Cleavage between the Gly and Ser residues of the reactive site loop and detection of a stable SCCA1-cathepsin S complex by sodium dodecyl sulfate-polyacrylamide gel electrophoresis suggested that the serpin interacted with the cysteine proteinase in a manner similar to that observed for typical serpin-serine proteinase interactions. These data suggest that, contingent upon their reactive site loop sequences, mammalian serpins, in general, utilize their dynamic tertiary structure to trap proteinases from more than one mechanistic class and that SCCA1, in particular, may be involved in a novel inhibitory pathway aimed at regulating a powerful array of lysosomal cysteine proteinases.
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PMID:Cross-class inhibition of the cysteine proteinases cathepsins K, L, and S by the serpin squamous cell carcinoma antigen 1: a kinetic analysis. 954 57

The importance of the evolutionarily conserved Gly-4 residue for the affinity and kinetics of interaction of cystatin A with several cysteine proteinases was assessed by site-directed mutagenesis. Even the smallest replacement, by Ala, resulted in approximately 1000-, approximately 10- and approximately 6000-fold decreased affinities for papain, cathepsin L, and cathepsin B, respectively. Substitution by Ser gave further 3-8-fold reductions in affinity, whereas the largest decreases, >10(5)-fold, were observed for mutations to Arg and Glu. The kinetics of inhibition of papain by the mutants with small side chains, Ala and Ser, were compatible with a one-step bimolecular reaction similar to that with wild-type cystatin A. The decreased affinities of these mutants for papain and cathepsin L were due exclusively to increased dissociation rate constants, but the reduced affinities for cathepsin B were due also to decreased association rate constants. The latter finding indicates that the intact N-terminal region serves as a guide directing cystatin A to the active site of cathepsin B, as has been proposed for cystatin C. The kinetics of binding of the mutants with charged side chains, Arg and Glu, to papain were consistent with a two-step binding mechanism, in which the mutant side chains are accommodated in the complex by a conformational change. The NMR solution structure of the Ala and Trp mutants showed only minor changes compared with wild-type cystatin A, indicating that the large reductions in affinity for proteinases are not due to altered structures of the mutants. Instead, a side chain larger than a hydrogen atom at position 4 affects the interaction with the proteinase most likely by interfering with the binding of the N-terminal region.
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PMID:The role of Gly-4 of human cystatin A (stefin A) in the binding of target proteinases. Characterization by kinetic and equilibrium methods of the interactions of cystatin A Gly-4 mutants with papain, cathepsin B, and cathepsin L. 958 70

The cystatin superfamily of cysteine protease inhibitors and target cysteine proteases such as cathepsin B have been implicated in malignant progression. The respective cellular/extracellular localization of cystatins and cysteine proteases in tumors may be critical in regulating activity of the enzymes. Confocal microscopy has enabled us to demonstrate the differential localization of cystatins and cathepsin B in an embryonic liver cell line and an invasive hepatoma cell line. In both, stefins A and B were distributed diffusely throughout the cytoplasm, whereas cystatin C was distributed in juxtanuclear vesicles. Stefin A and cystatin C, but not stefin B, were present on the cell surface. Cystatin C was found on the top surfaces of both cell lines, whereas stefin A was found only on the top surface of the embryonic liver cells. Cathepsin B staining was concentrated in perinuclear vesicles in the embryonic liver cells. In the hepatoma cells, staining for cathepsin B was also present in vesicles adjacent to the cell membrane and on localized regions of the bottom surface. Such a disparate distribution of cathepsin B and its endogenous inhibitors may facilitate proteolysis by the hepatoma cells and thereby contribute to their invasive phenotype.
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PMID:Differential localization of cysteine protease inhibitors and a target cysteine protease, cathepsin B, by immuno-confocal microscopy. 960 86

This study examined the role of cysteine proteinases and their inhibitor in the development of emphysema in comparison with neutrophil elastase (NE) complexed with alpha1-protease inhibitor (NE-alpha1-PI), which was previously demonstrated to be increased in bronchoalveolar lavage (BAL) fluid from subjects with subclinical emphysema. Eight nonsmokers and 31 current smokers with (n=17) and without (n=14) emphysema, as evidenced by lung computed tomographic scans, were studied. The concentrations of immunologically detected cathepsin L and cystatin C, but not cathepsin B, were significantly increased in BAL fluid from the smokers with emphysema compared with those without emphysema, although the activity of cathepsin L, measured using a synthetic substrate and cathepsin L, released from cultured alveolar macrophages at 24 h, did not show any significant difference between the two groups. When comparison was made only for the subjects aged <60 yrs, the difference between the two groups disappeared for cathepsin L, but remained for NE-alpha1-PI. There was no significant correlation between the level of cathepsin L and that of NE-alpha1-PI in BAL fluid from the subjects with emphysema. In conclusion, increased levels of cathepsin L and cystatin C were demonstrated in bronchoalveolar lavage fluid from subjects with subclinical emphysema. However, the roles of cathepsin L and neutrophil elastase in the development of emphysema may vary between subjects and between the young and the old.
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PMID:Cysteine proteinases and cystatin C in bronchoalveolar lavage fluid from subjects with subclinical emphysema. 986 93

We investigated whether cystatins and cystatin-derived peptides, encompassing sequences of secondary structures of cystatin S and papain binding domains of cystatin C, display antimicrobial properties. Of the different microorganisms tested, only the growth of P. gingivalis was inhibited by chicken cystatin and cystatin C. Cystatin S, cystatin S:1-14, cystatin S:61-73 and cystatin S:108-121 also inhibited its growth, whereas cystatin S:21-38, cystatin S:39-55, cystatin S:81-95, cystatin S:94-109, and cystatin C: 9-12/55-60/106-107 did not. No inhibition of the cysteine proteinase activity of P. gingivalis was observed for all cystatin-derived peptides. On the other hand, leupeptin and antipain inhibited P. gingivalis proteinase activity, but had no effect on the growth. These data suggest that cystatins contain antibacterial sequences active against P. gingivalis and that the growth inhibition does not depend on the inhibition of P. gingivalis cysteine proteinases.
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PMID:Cystatin and cystatin-derived peptides have antibacterial activity against the pathogen Porphyromonas gingivalis. 986 12

Cystatin C is one of a family of proteinase inhibitors of cathepsins and other cysteine proteinases. Among warm-blooded vertebrates, small functional regions of cystatin amino acid sequences are well conserved among species, but major portions of cystatin amino acid sequences vary evolutionarily. Although considerable attention has been given to mammalian and avian cystatins, little data exist on cystatins from other vertebrates. A cDNA clone for trout cystatin C was isolated from a lambda gt11 cDNA library of rainbow trout (Oncorhynchus mykiss) liver. An apparently full-length cDNA clone of 674 bp encoding 132 amino acid residues was obtained. Sequence analysis indicated that trout cystatin C contains an N-terminal signal sequence extension of 21 amino acids and a mature sequence of 111 amino acid residues, with amino acid residues conserved in functional regions relative to mammalian and avian cystatin C. Using cloned cDNA as a probe, we investigated expression of the cystatin C gene in trout tissues, several cell lines of trout liver or liver tumor, and cell cultures of liver tumor origin. Cystatin C mRNA was in high abundance in trout embryo tissue, a tumor-derived liver cell line and some normal adult tissues. Southern hybridization analysis indicated one copy of the trout cystatin C gene per haploid genome, and sequence comparisons indicated considerable divergence in large portions of the coding region of the trout cystatin C gene relative to a variety of species.
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PMID:Molecular cloning, sequence analysis and expression distribution of rainbow trout (Oncorhynchus mykiss) cystatin C. 997 89

We have investigated the inhibition of the recently identified family C13 cysteine peptidase, pig legumain, by human cystatin C. The cystatin was seen to inhibit enzyme activity by stoichiometric 1:1 binding in competition with substrate. The Ki value for the interaction was 0.20 nM, i.e. cystatin C had an affinity for legumain similar to that for the papain-like family C1 cysteine peptidase, cathepsin B. However, cystatin C variants with alterations in the N-terminal region and the "second hairpin loop" that rendered the cystatin inactive against cathepsin B, still inhibited legumain with Ki values 0.2-0.3 nM. Complexes between cystatin C and papain inhibited legumain activity against benzoyl-Asn-NHPhNO2 as efficiently as did cystatin C alone. Conversely, cystatin C inhibited papain activity against benzoyl-Arg-NHPhNO2 whether or not the cystatin had been incubated with legumain, strongly indicating that the cystatin inhibited the two enzymes with non-overlapping sites. A ternary complex between legumain, cystatin C, and papain was demonstrated by gel filtration supported by immunoblotting. Screening of a panel of cystatin superfamily members showed that type 1 inhibitors (cystatins A and B) and low Mr kininogen (type 3) did not inhibit pig legumain. Of human type 2 cystatins, cystatin D was non-inhibitory, whereas cystatin E/M and cystatin F displayed strong (Ki 0.0016 nM) and relatively weak (Ki 10 nM) affinity for legumain, respectively. Sequence alignments and molecular modeling led to the suggestion that a loop located on the opposite side to the papain-binding surface, between the alpha-helix and the first strand of the main beta-pleated sheet of the cystatin structure, could be involved in legumain binding. This was corroborated by analysis of a cystatin C variant with substitution of the Asn39 residue in this loop (N39K-cystatin C); this variant showed a slight reduction in affinity for cathepsin B (Ki 1.5 nM) but >>5,000-fold lower affinity for legumain (Ki >>1,000 nM) than wild-type cystatin C.
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PMID:Inhibition of mammalian legumain by some cystatins is due to a novel second reactive site. 1038 26

Cystatin C with the 11 N-terminal amino acids truncated shows a much lower affinity for cysteine proteinases than the intact inhibitor. Such truncation of cystatin C is recorded after action of glycyl endopeptidase and cathepsin L. Incubation of cystatin C with papain, cathepsin B or cathepsin H led to no changes in the cystatin C molecule. Isoelectric focusing of the cathepsin L and cystatin C mixture showed the formation of two new bands. One of them appeared whether E-64 or PMSF was added or not, evidently representing a cystatin C/cathepsin L complex. The other band is the truncated cystatin C molecule. N-terminal sequencing after separation by HPLC showed that cystatin C is cleaved by cathepsin L at the Gly11-Gly12 bond. The action of cathepsin L on cystatin C may be explained by the cleavage of the scissile bond in an inappropriate complex.
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PMID:Cathepsin L is capable of truncating cystatin C of 11 N-terminal amino acids. 1042 79


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