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)

Hereditary cerebral hemorrhage with amyloidosis, Dutch type (HCHWA-D) (or familial cerebral amyloid angiopathy) and familial Alzheimer's disease (FAD) share several properties. Both are autosomal dominant forms of cerebral amyloidosis characterized by beta-amyloid (A beta) deposition. In HCHWA-D the A beta is predominantly found in blood vessels and in early parenchymal plaques, whereas in AD parenchymal A beta deposits in the form of senile plaques and neurofibrillary tangles are a more prominent finding. Point mutations in the amyloid precursor protein (APP) have recently been described, in both conditions. A G to C transversion at codon 618 (extracellular portion of APP695), producing a single amino acid substitution of glutamine instead of glutamine acid, occurs in HCHWA-D; whereas mutations at codon 642 in the intramembrane region of APP695 (phenylalanine, isoleucine, or glycine instead of valine) are associated with early onset FAD. This suggests that the site of particular mutations in the APP gene and the type of amino acid substitution in the APP holoprotein are more important in determining clinicopathological phenotype and age at which A beta is deposited. Thus FAD and HCHWA-D can be regarded as two sides of the same coin.
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PMID:Molecular biology of Alzheimer's amyloid--Dutch variant. 146 89

mRNA from a postmortem liver sample of a patient with classical phenylketonuria was examined using the chemical cleavage of mismatch (CCM) method to search for mutations in phenylalanine hydroxylase. Initial screening identified a heterozygous alteration in exon 2 which changed the encoded amino acid from phenylalanine (TTC) to leucine (TTG) at codon 39 and a polymorphism at codon 430 where the change from CTG to CTC did not alter the encoded leucine. Use of the CCM technique also revealed that the control reference clone differed from the published sequence by having a substitution of isoleucine (ATT) for methionine (ATG) at codon 276 and CAA rather than CAG as the codon for glutamine 232. By using the mRNA from the patient instead of the control as the source for the radiolabeled probe for the CCM technique, a second previously undetected alteration was identified in exon 10 where the change from TCA to CCA at codon 349 altered the amino acid from serine to arginine. Judicious choice of probes gives the CCM method the potential to detect close to 100% of single base mutations.
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PMID:Mutation detection in phenylketonuria by using chemical cleavage of mismatch: importance of using probes from both normal and patient samples. 206 69

Procathepsin L, the precursor to a powerful lysosomal cysteine proteinase, has been purified to apparent homogeneity from guinea pig spermatozoa, a novel and previously unrecognized source of this catalytically active zymogen. In the range of pH 5.0, procathepsin L (39,000 M(r)) readily self-processed yielding a mature, single-chain proteinase (29,000 M(r)) and an intact propeptide (10,000 M(r)) by what appeared kinetically to be an intramolecular reaction mechanism. These characteristics resembled those reported for the "major excreted protein" (MEP) of malignantly transformed mouse fibroblasts-a protein that has been characterized as the precursor to the mouse analog of human cathepsin L (B. R. Troen, S. Gal, and M. M. Gottesman (1987) Biochem. J. 246, 731-735). Other characteristics shared by the guinea pig and mouse zymogens included proteolytic activity at pH 5.0, homologous N-terminal amino acid sequences, and immunological relatedness. It was thus concluded that acrosomal procathepsin L is the guinea pig analog of MEP. Acrosomal procathepsin L had a specific activity on benzyloxy-carbonyl-Phe-Arg-7-(4-methyl)coumarylamide (Z-Phe-Arg-NMec) of 30 mumol min-1 mg-1 enzyme at pH 3.2 and 37 degrees C. Relative to the assay substrate, rates on other fluorogenic substrates were 90% for Z-Phe-Cit-NMec, 63% for Z-Leu-Leu-Arg-NMec, 43% for D-Phe-Ser(Bzl)-Phe-Phe-Ala-Ala-p-aminobenzoate (a "specific" cathepsin D assay substrate), and 32% for Z-Val-Val-Arg-NMec. No action was detected on Z-Arg-Arg-NMec or Arg-NMec. Mature cathepsin L showed the same relative order of substrate specificity as its proenzyme form, but the absolute rates were about 5-fold greater. Additionally, the mature (single-chain) form of cathepsin L displayed Km and kcat values on Z-Phe-Arg-NMec that yielded an exceptionally high catalytic coefficient (11,600 s-1 mM-1) compared to values reported for two-chain forms of cathepsin L. Self-processing by acrosomal procathepsin L at pH 5.5 was totally inhibited by leupeptin, cystatin C, Ep-475, and Z-Phe-Phe-CHN2 at 1 microM levels. Gossypol (0.1 mM) gave 94% inhibition. Interestingly, dextran sulfate (100 micrograms ml-1) gave a 3.6-fold increase in the rate of self-processing seen at pH 5.5--a phenomenon of potential physiological relevance in view of the high-negative-charge density present within the hyaluronic acid-rich outer layer (cumulus oophorus) of the ovum.
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PMID:Purification and characterization of procathepsin L, a self-processing zymogen of guinea pig spermatozoa that acts on a cathepsin D assay substrate. 748 6

'Prohormone thiol protease' (PTP) represents the major enkephalin precursor processing activity in chromaffin granules. In this study, cleavage specificity of PTP for paired basic and monobasic residues was examined with a series of model peptide-MCA (-methylcoumarinamide) substrates. Monobasic peptides were cleaved at the COOH- and NH2-terminal sides of the single basic residue. Dibasic peptides, however, were preferentially cleaved at the NH2-terminal side of the pair, or between the two basic residues, with low cleavage at the COOH-terminal side of the pair. Inhibition by the peptide inhibitor (D-Tyr)-Glu-Phe-Lys-Arg-CH2Cl provided further evidence for PTP's specificity for the dibasic Lys-Arg site. Inhibition by Z-Leu-Val-Gly-CHN2 and Z-Arg-Leu-Val-Gly-CHN2 suggests involvement of Val-Gly in substrate binding to PTP; these two cystatin C-related inhibitors also indicate PTP as a cysteine protease. These results demonstrate PTP's unique cleavage specificity that differs from other processing endopeptidases, including the subtilisin-related proprotein convertases, PC1/PC3, and PC2, as well as the pituitary proopiomelanocortin-converting enzyme, PCE. This study provides further evidence for PTP as a novel prohormone processing enzyme that belongs to the class of cysteine proteases.
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PMID:Unique cleavage specificity of 'prohormone thiol protease' related to proenkephalin processing. 813 39

The 5' context of 671 Escherichia coli stop codons UGA and UAA has been compared with the context of stop-like codons (UAC, UAU and CAA for UAA; UGG, UGC, UGU and CGA for UGA). We have observed highly significant deviations from the expected nucleotide distribution: adenine is over-represented whereas pyrimidines are under-represented in position -2 upstream from UAA. Uridine is over-represented in position -3 upstream from UGA. Lysine codons are preferable immediately prior to UAA. A complete set of codons for serine and the phenylalanine UUC codon are preferable immediately 5' to UGA. This non-random codon distribution before stop codons could be considered as a molecular device for modulation of translation termination. We have found that certain fragment of E. coli release factor 2 (RF2) (amino acids 93-114) is similar to the amino acid sequences of seryl-tRNA synthetase (positions 10-19 and 80-93) and of beta (small) subunit (positions 72-94) of phenylalanyl-tRNA synthetase from E. coli. Three-dimensional structure of E. coli seryl-tRNA synthetase is known [1]: Its N-terminus represents an antiparallel alpha-helical coiled-coil domain and contains a region homologous to RF2. On the basis of the above-mentioned results we assume that a specific interaction between RF2 and the last peptidyl-tRNA(Ser/Phe) occurs during polypeptide chain termination in prokaryotic ribosomes.
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PMID:Termination of translation in bacteria may be modulated via specific interaction between peptide chain release factor 2 and the last peptidyl-tRNA(Ser/Phe). 833 98

The nearest 5' context of 2559 human stop codons was analysed in comparison with the same context of stop-like codons (UGG, UGC, UGU, CGA for UGA; CAA, UAU, UAC for UAA; and UGG, UAU, UAC, CAG for UAG). The non-random distribution of some nucleotides upstream of the stop codons was observed. For instance, uridine is over-represented in position -3 upstream of UAG. Several codons were shown to be over-represented immediately upstream of the stop codons: UUU(Phe), AGC(Ser), and the Lys and Ala codon families before UGA; AAG(Lys), GCG(Ala), and the Ser and Leu codon families before UAA; and UCA(Ser), AUG(Met), and the Phe codon family before UAG. In contrast, the Thr and Gly codon families were under-represented before UGA, while ACC(Thr) and the Gly codon family were under-represented before UAG and UAA respectively. In an earlier study, uridine was shown to be over-represented in position -3 before UGA in Escherichia coli [Arkov,A.L., Korolev,S.V. and Kisselev,L.L. (1993) Nucleic Acids Res., 21,2891-2897]. In that study, the codons for Lys, Phe and Ser were shown to be over-represented immediately upstream of E. coli stop codons. Consequently, E. coli and human termination codons have similar 5' contexts. The present study suggests that the 5' context of stop codons may modulate the efficiency of peptide chain termination and (or) stop codon readthrough in higher eukaryotes, and that the mechanisms of such a modulation in prokaryotes and higher eukaryotes may be very similar.
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PMID:5' contexts of Escherichia coli and human termination codons are similar. 852 65

We report three novel mutations of the thyroid hormone receptor beta (TR beta) gene in three unrelated Japanese patients with resistance to thyroid hormone (RTH). Patients A and B exhibited generalized resistance phenotype, while patient C displayed more pituitary-selective unresponsiveness. Direct sequencing of TR beta gene exon 10 disclosed novel point mutations in all three patients. A Phe to Ile (TTC-->ATC) substitution at codon 451, a His to Leu (CAT-->CTT) substitution at codon 435, and a His to Gln (CAT-->CAA) substitution at codon 435 were identified in patients A, B, and C, respectively. Sequencing of TR beta gene exons 5-9 as well as TR alpha gene exons 4-9 failed to detect any additional mutations. All three patients were heterozygous for respective mutations. The unaffected parents of patients A and B, having normal thyroid function, possessed no mutations of TR beta gene exon 10, indicating that the F451I and H435L mutations occurred de novo. The F451I mutation is located near the most frequent mutation site in the ligand 2 subdomain. The identical codon mutations H435L and H435Q, which lie at the extreme carboxyl-terminus of the dimerization subdomain near the 9th heptad, were found in clinically different subtypes of RTH: patient B with generalized resistance and patient C with pituitary-selective resistance, respectively. The mutations broaden the growing catalogue of the TR beta gene mutations that could cause different phenotypes, despite the defects at the same codon.
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PMID:Three novel mutations of thyroid hormone receptor beta gene in unrelated patients with resistance to thyroid hormone: two mutations of the same codon (H435L and H435Q) produce separate subtypes of resistance. 853 Jun 8

The single Trp of human cystatin C, Trp-106, is located in the second hairpin loop of the proteinase binding surface. Substitution of this residue by Gly markedly altered the spectroscopic changes accompanying papain binding and reduced the affinity for papain, actinidin, and cathepsins B and H by 300-900-fold. The decrease in affinity indicated that the side chain of Trp-106 contributes a similar free energy, -14 to -17 kJ.mol-1, to the binding to all four cysteine proteinases, corresponding to about 20-30% of the total binding energy. Replacement of Trp-106 by Phe led to a smaller (30-120-fold) decrease in affinity for the four enzymes than Gly substitution. The binding energy of the Phe residue corresponded to 20-45% of that of Trp, showing that a phenyl group can only partly substitute for the indole ring. The reduced affinities of the cystatin C Trp-106 variants for all proteinases studied were due almost exclusively to increased dissociation rate constants. The second hairpin loop thus contributes to the binding primarily by keeping cystatin C anchored to the proteinase once the complex has been formed. This role is partly in contrast to that of the N-terminal region, which increases the affinity of cystatin C for cathepsin B by increasing the association rate constant. Removal of the N-terminal region of the Trp-106-->Gly variant by proteolytic cleavage substantially weakened the binding to papain and cathepsin B. The resulting affinity indicated that the first hairpin loop (the "QVVAG-region"), which is the only region of the proteinase binding surface remaining intact in the truncated variant, contributes 40-60% of the total free energy of binding of cystatin C to both proteinases.
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PMID:The importance of the second hairpin loop of cystatin C for proteinase binding. Characterization of the interaction of Trp-106 variants of the inhibitor with cysteine proteinases. 871 61

We used site-directed mutagenesis to alter the specificity of human cystatin C, an inhibitor with a broad reactivity against cysteine proteinases. Nine cystatin C variants containing amino acid substitutions in the N-terminal (L9W, V10W, V10F and V10R) and/or the C-terminal (W106G) enzyme-binding regions were designed and produced in Escherichia coli. It was discovered that the inhibition profile of the cystatin could be altered by changing residues 9 and 10, which are proposed to bind in the S3 and S2 substrate-binding pockets respectively of the enzymes. All of the variants with substitutions in the N-terminal segment displayed decreased binding to cathepsins B and H, indicating that the S3 and S2 pockets of these enzymes cannot easily accommodate large aromatic residues. The introduction of a charged residue into S2 (variant V10R) created a more specific inhibitor to distinguish cathepsin B from cathepsin H. Cathepsin L showed a preference for larger aromatic residues in S2. In contrast, cathepsin S preferred phenylalanine to valine in S2, but bound less tightly to the V10W cystatin variant. The latter variant proved to be valuable for discriminating between cathepsin L and cathepsin S (Ki 2.4 and 190 pM respectively). The equilibrium dissociation constant of the complex between cathepsin L and variant L9W/W106G showed little difference in affinity from that of the cathepsin L complex with the singly substituted W106G variant. In contrast, the L9W/W106G variant displayed increased specificity for cathepsin S with a Ki of 10 pM. Our results clearly indicate differences in the specificity of interaction between the N-terminal region of cystatin C and cathepsins B, H, L and S, and that, although cystatin C has evolved to be a good inhibitor of all of the mammalian cysteine proteinases, more specific inhibitors of the individual enzymes can be engineered.
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PMID:Amino acid substitutions in the N-terminal segment of cystatin C create selective protein inhibitors of lysosomal cysteine proteinases. 948 Aug 98

We analysed the molecular basis of Glanzmann thrombasthenia (GT) in four Japanese patients with type I or type II disease. Polymerase chain reaction (PCR) and subsequent direct sequencing of platelet RNA and genomic DNA revealed three single nucleotide substitutions of the alphaIIb gene, which were confirmed by allele-specific PCR or restriction analysis. One patient with type I GT had a T to C base substitution in exon 11 resulting in a Phe (TTT)-289 to Ser (TCT) mutation (F289S) of the subunit. Another type I patient had a G to A base substitution in exon 12 resulting in a Glu (GAA)-324 to Lys (AAA) mutation (E324K). Interestingly, two unrelated patients with type II GT shared an A to C base substitution in exon 2 3, a region previously not associated with GT, resulting in a Gln (CAA)-747 to Pro (CCA) mutation (Q747P). To analyse the effects of these mutations on alphaII(b)beta3 surface expression, the wild-type alphaIIb cDNA or mutant alphaIIb cDNAs were transfected into Chinese hamster ovary (CHO) cells together with a wild-type beta3 cDNA. Flow cytometric analysis using an anti-alphaII(b)beta3 complex antibody revealed that 50.6% of CHO cells with wild-type alphaII(b)beta3 expressed complexes, whereas only 1 6%, 7.7% and 31.3% of cells, with IIb(F289S)beta3, alphaIIb(E324K)beta3 and alphaIIb(Q747P)beta3 expressed complexes, respectively. Our data indicate that these three novel point mutations in the alphaIIb subunit may hamper surface expression of the alphaII(b)beta3 complex, thus resulting in the quantitative GT phenotypes of platelets from these patients.
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PMID:Novel point mutations in the alphaIIb subunit (Phe289-->Ser, Glu324-->Lys and Gln747-->Pro) causing thrombasthenic phenotypes in four Japanese patients. 972 14


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