Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. RNase St was inactivated by iodoacetate. The inactivation was most rapid at pH 5.0-7.0. Competitive inhibitors protected RNase St from inactivation by iodoacetate. The protective effect of 2'-GMP was most effective among nucleotides tested. 2. RNase St was inactivated with the concomitant incorporation of one molar equivalent of carboxymethyl group. The carboxymethyl group incorporated into RNase St was liberated by treatment with 0.2 N NaOH or 1 M hydroxylamine. Thus the incorporation of a carboxymethyl group into a carboxyl group was demonstrated. 3. 14C-labeled CM-RNase St was digested successively with alkaline protease and aminopeptidase M. The 14C-labeled amino acid was identified as the carboxymethyl ester of glutamic acid by means of column chromatography. 4. By digestion of reduced carboxymethylated CM-RNase St with trypsin, a peptide containing a 14C-carboxymethyl group was isolated by Dowex AG-50W colum chromatography. alpha-Chymotryptic digestion of the radioactive tryptic peptide, Glu48-Lys65, produced a tetrapeptide containing a 14C-carboxymethyl group, that is, Tyr59-His60-Glu61-Tyr62. Therefore, it was concluded that Glu61 in RNase St was the site of carboxymethylation. 5. When RNase St was inactivated by iodoacetamide at pH 8.0, about 2 histidine residues were modified. The molar ratio of the products of carboxyamidomethylation were 52.3%, 21.7%, 21.0%, and 4.8% for 3-CAM-His, 1,3-di-CAM-His, 1-CAM-His, and di-CM-Lys, respectively. 6. CD spectra of CM-RNase St and CAM-RNase St were practically the same as that of the native RNase St indicating the maintenance of the native conformation during modification. 7. The binding constants of CM-RNase St and CAM-RNase St with 2'-GMP were about 1/150 and 1/38 of that of the native enzyme, respectively.
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PMID:Alkylation of a ribonuclease from Streptomyces erythreus with iodoacetate and iodoacetamide. 728 72

A series of Southern blot hybridization experiments using probes derived from different regions of the rat liver cell-cell adhesion molecule 105 (C-CAM) cDNA revealed the presence of a 9.6 kb EcoRI genomic fragment that seemed to encode a unique C-CAM isoform. An RNase protection study showed that this c-CAM transcript was expressed in placenta, spleen, lung and large intestine. In contrast, the other C-CAM isoforms, C-CAM1 and C-CAM2, are expressed in liver and small intestine. This result also suggests that the new isoform, which we named C-CAM4, was indeed encoded by a new C-CAM gene. A rat placenta cDNA library was then screened and the full-length cDNA coding for C-CAM4 was isolated. The deduced protein contained 142 amino acids and had a calculated molecular mass of 15 kDa. C-CAM4 was composed of a leader sequence and the first V-like Ig domain typical of C-CAM-family proteins. However, C-CAM4 lacked the C-like Ig domains, the transmembrane domain, and the cytoplasmic domain found in other C-CAM isoforms. Thus, C-CAM4 is different from the other known C-CAMs in that it is a secreted protein. We have previously shown that the first Ig domain of C-CAM1 is crucial for its adhesion function. The V-like Ig domain of C-CAM4 had 92% and 89% sequence identity with the corresponding regions of C-CAM1 and C-cam2 respectively. Together these results suggest that C-CAM4 may play a role in regulating the function of other C-CAM family proteins.
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PMID:Identification of a new isoform of cell-cell adhesion molecule 105 (C-CAM), C-CAM4: a secretory protein with only one Ig domain. 864 60

Biliary glycoprotein (BGP, CD66a, or C-CAM-1) is a cell adhesion glycoprotein expressed in colon, liver, and hematopoietic tissues. Four major isoforms (a-d) of BGP are expressed in most epithelial tissues by alternative mRNA splicing from a single gene. Since BGP is down regulated in colon cancer and in premalignant colonic adenomas, it has been of interest to study its expression in other tumors. Using immunohistochemistry with a BGP specific antibody, and mRNA analysis by in situ hybridization, RNase protection, and RT-PCR, we show here that BGP is expressed to the same extent in both normal and malignant breast, demonstrating that BGP is not down regulated in breast cancer. In normal breast, BGP expression is confined to the apical surface of ductal and lobular epithelial cells, while in invasive carcinoma of the breast, BGP is expressed throughout the cytoplasm. In situ hybridization shows a specific pattern of BGP expression in both normal and malignant breast epithelium. RNase protection analysis confirms the immunohistochemistry results and shows no quantitative differences between normal and malignant breast. RT-PCR analysis agrees with these results and shows that only 3 of the 4 major isoforms (a, c, d) of BGP are expressed in normal and malignant breast. Since recent studies by Turbide et al (Cancer Res 57: 2781-2788, 1997) have shown that the ratio of murine BGP isoforms may affect tumor suppression in colonic cancer, it is proposed here that the isoform difference between human breast and colon may account for the observed lack of BGP down-regulation in breast vs colon cancer.
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PMID:Expression of biliary glycoprotein (CD66a) in normal and malignant breast epithelial cells. 985 84

C-CAM is an epithelial cell adhesion molecule with two major splice variants that differ in the length of the cytoplasmic domain. C-CAM1 (long (L)-form) strongly suppresses the tumorigenicity of human prostate carcinoma cells. In contrast, C-CAM2 (short (S)-form) does not exhibit tumor-suppressive activity. In the present study we have investigated the functional significance of L-form and S-form C-CAM in rat prostate by examining their expression and distribution in different prostate lobes and their response to androgen deprivation. RNase protection assays with a probe for both C-CAM isoforms detected high levels of C-CAM messages in the rat dorso-lateral prostate (DLP). L- and S-form proteins, localized by indirect immunofluorescence using isoform-specific antipeptide antibodies, were co-expressed on the apical surface of prostate epithelial cells in normal DLP. Androgen depletion did not significantly change the steady state levels of C-CAM message and protein expression in the DLP, although there was a change in the pattern of protein expression in these lobes. In contrast, C-CAM isoform messages and proteins were undetectable in normal ventral prostate (VP) but increased markedly in this lobe in response to castration, producing isoform ratios similar to those in DLP. These results demonstrate that coordinate expression of C-CAM isoforms is maintained in the VP following androgen depletion and suggest that androgen suppresses C-CAM expression in VP but not in DLP. These results suggest that balanced expression of L- and S-form C-CAM is important for normal prostate growth and differentiation.
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PMID:Expression and androgen regulation of C-CAM cell adhesion molecule isoforms in rat dorsal and ventral prostate. 1035 31

A growing number of pancreatic-type ribonucleases (RNases) present cytotoxic activity against malignant cells. The cytoxicity of these enzymes is related to their resistance to the ribonuclease protein inhibitor (RI). In particular, bovine seminal ribonuclease (BS-RNase) is toxic to tumor cells both in vitro and in vivo. BS-RNase is a covalent dimer with two intersubunit disulfide bridges between Cys(31) of one chain and Cys(32) of the second and vice versa. The native enzyme is an equilibrium mixture of two isomers, MxM and M=M. In the former the two subunits swap their N-terminal helices. The cytotoxic action is a peculiar property of MxM. In the reducing environment of cytosol, M=M dissociates into monomers, which are strongly inhibited by RI, whereas MxM remains as a non-covalent dimer (NCD), which evades RI. We have solved the crystal structure of NCD, carboxyamidomethylated at residues Cys(31) and Cys(32) (NCD-CAM), in a complex with 2'-deoxycitidylyl(3'-5')-2'-deoxyadenosine. The molecule reveals a quaternary structural organization much closer to MxM than to other N-terminal-swapped non-covalent dimeric forms of RNases. Model building of the complexes between these non-covalent dimers and RI reveals that NCD-CAM is the only dimer equipped with a quaternary organization capable of interfering seriously with the binding of the inhibitor. Moreover, a detailed comparative structural analysis of the dimers has highlighted the residues, which are mostly important in driving the quaternary structure toward that found in NCD-CAM.
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PMID:Structure and stability of the non-covalent swapped dimer of bovine seminal ribonuclease: an enzyme tailored to evade ribonuclease protein inhibitor. 1519 98