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

In this study we have confirmed the presence of a single base difference between intestinal mRNA coding for B-48 and hepatic mRNA coding for B-100, which results in the substitution of a stop codon (UAA) for a glutamine codon (CAA) at a point corresponding to amino acid residue 2153 in the B-100 sequence. Based on this finding, B-48 is predicted to terminate at residue 2152 with the sequence ... Met Ile. To confirm this finding at the protein level, B-48 and B-100 were each digested with cyanogen bromide and the digestion products were analysed for the presence of isoleucine. Isoleucine was found only in cyanogen bromide digests of B-48 confirming that only B-48 terminates with the predicted amino acid sequence ... Met Ile.
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PMID:Carboxyl terminal analysis of human B-48 protein confirms the novel mechanism proposed for chain termination. 342 12

Two different isoproteins are encoded by the apolipoprotein (apo) B gene, apoB-48 and apoB-100. ApoB-48, core component of intestinally derived chylomicrons, has an accelerated plasma turnover as compared with the full-length protein apoB-100. A posttranscriptional modification of the apoB mRNA by conversion of cytidine into uridine at nucleotide position 6666 changes the genomically encoded glutamine codon CAA at amino acid residue 2153 into a translational stop codon UAA. This mRNA editing explains the formation of the truncated isoform apoB-48. In the present investigation editing of apoB mRNA in liver and intestine from 12 different mammalian species was measured by a quantitative primer extension analysis of reverse-transcribed and polymerase chain reaction- (PCR) amplified apoB mRNA in order to determine whether i) editing of apoB mRNA is generally restricted to the intestine or may also be found in the liver of other species than rodents, and ii) hepatic expression of apoB mRNA editing influences lipoprotein concentrations in plasma. Intestinal apoB mRNA was edited at high levels in all species, 40% in sheep, 73% in horse, 82% in pig, 84% in dog, 84% in cat, 87% in guinea pig, 88% in rat, 89% in mouse, and > 90% in human, monkey, cow, and rabbit. In liver apoB mRNA was edited to 18% in dog, to 43% in horse, to 62% in rat, and to 70% in mouse. Low levels of editing below 1% were detected in liver of rabbit and guinea pig. In contrast, hepatic apoB mRNA from human, monkey, pig, cow, sheep, and cat liver was not edited. The results of the primer extension analysis were confirmed by cloning and sequencing of the PCR products from dog, horse, cat, guinea pig, sheep, and cow for all of which the apoB cDNA sequence had not been established by previous investigations. Primer extension analysis of apoB mRNA from dog intestine and dog liver indicated C/U editing at C6655 in addition to C6666. Cloning and sequencing of apoB cDNA from dog liver and intestine confirmed additional C/U editing at C6655 which changes ACA for threonine at amino acid residue 2149 into AUA for isoleucine. Synthesis and secretion of apoB-48-containing lipoproteins from liver was demonstrated by pulse labeling of freshly isolated horse hepatocytes and immunoprecipitation with apoB-specific antibodies or density gradient ultracentrifugation. The concentrations of VLDL, LDL, and HDL in all species were determined after fractionation by density gradient ultracentrifugation.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Apolipoprotein B mRNA editing in 12 different mammalian species: hepatic expression is reflected in low concentrations of apoB-containing plasma lipoproteins. 840 68

We cloned a protein phosphatase 2C gene from Paramecium (PtPP2C), which codes for one of the smallest PP2C isoforms (Klumpp, S., Hanke, C., Donella-Deana, A., Beyer, A., Kellner, R., Pinna, L. A., and Schultz, J. E. (1994) J. Biol. Chem. 269, 32774-32780). After mutation of 9 ciliate Q codons (TAA) to CAA PtPP2C was expressed as an active protein in Escherichia coli. The catalytic core region contains 284 amino acids as defined by C- and N-terminal deletions. The C terminus from amino acid 200-300 of PP2C isoforms has only about 20% similarity. To demonstrate that the carboxy end is in fact needed for activity, we generated an enzymatically active PtPP2C containing a C-terminally located tobacco etch virus-protease site. Upon proteolytic truncation enzyme activity was lost, i.e. the C terminus of PP2C is indispensable for enzyme activity. During these experiments isoleucine 214 was fortuitously identified to be essential for PP2C catalysis. Mutation of the hydrophobic amino acid to glycine in the ciliate or bovine isoforms resulted in inactive protein. Because Ile214 is in a loop region without defined secondary structure, our data clearly go beyond the x-ray structure. The functional equivalence of the 180 amino acid long C terminus from the bovine PP2C with the 100 amino acid long carboxy end of the PtPP2C was demonstrated by producing an active chimera, i.e. the PP2C from Paramecium has no obvious regions which may be specifically involved in subcellular localization or substrate recognition. Using antibodies against recombinant PtPP2C we localized the enzyme by immunogold labeling in the cytosol and nucleus and very distinctly on the ciliary microtubule/dynein complex. The data suggest a role for PtPP2C in the regulation of dyneins, i.e. in cellular cargo transport and ciliary motility.
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PMID:Functional characterization and localization of protein phosphatase type 2C from Paramecium. 966 3

Translation termination in vivo was studied in the yeast Saccharomyces cerevisiae using a translation-assay system. Codon changes that were made at position -2 relative to the stop codon, gave a 3.5-fold effect on termination in a release-factor-defective (sup45) mutant strain, in line with the effect observed in a wild-type strain. The influence of the -2 codon could be correlated to the charge of the corresponding amino acid residue in the nascent peptide; an acidic residue favoring efficient termination. Thus, the C-terminal end of the nascent peptide influences translation termination both in the bacterium Escherichia coli and to a lesser extent in the yeast S. cerevisiae. However, the sensitivity to the charge of the penultimate amino acid is reversed when the E. coli and S. cerevisiae are compared. Changing - 1 (P-site) codons in yeast gave a 10-fold difference in effect on the efficiency of termination. This effect could not be related to any property of the encoded last amino acid in the nascent peptide. Iso-codons read by the same tRNA (AAA/G, GAA/G) gave similar readthrough values. Codons for glutamine (CAA/G), glutamic acid (GAA/G) and isoleucine (AUA/C) that are read by different isoaccepting tRNAs are associated with an approximately twofold difference in each case in termination efficiency. This suggests that the P-site tRNA is able to influence termination at UGAC in yeast.
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PMID:The influence of 5' codon context on translation termination in Saccharomyces cerevisiae. 979 26

The membrane associated endoprotease, hRCE1, is responsible for one step in Ras membrane localization. The "CAAX" sequence at the C-terminal of farnesylated Ras proteins is cleaved by hRCE1 to yield an AAX tri-peptide. We found that an 8-aa K-Ras-derived "CAA" peptide, KSKTKC(farnesyl)VI, was a better substrate for hRCE1 than a KSKTKC(f)VIM "CAAX" peptide. When we examined hRCE1 activity on the same K-Ras core peptide with H-Ras (VLS) or N-Ras (VVM) C-terminal AAX sequences, we also found that in each case, the CAA peptides were better hRCE1 substrates. For each peptide set we examined, the P2' (A) and P3' (X) positions appeared independent in influencing hRCE1 activity on peptide substrates. We found that at the P3' position, methionine was better than serine; while at the P2' position, isoleucine and valine were better than leucine. Additionally, we found that a similar noncleaved peptide (modified at P'2 with a nitrophenyl group) could act as a competitive inhibitor of the reaction. Thus, hRCE1 has important functional interaction with the P2' and P3' substrate positions in addition to the farnesylated cysteine at the scissile bond site. This data could be useful in design of peptidomimetic inhibitors of hRCE1. Such inhibitors may be useful in treatment of cancer and inflammatory disease.
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PMID:Human Ras converting enzyme endoproteolytic specificity at the P2' and P3' positions of K-Ras-derived peptides. 1281 87