Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We examined the properties of a new iron-binding protein purified previously from rat liver (T. Furukawa, S. Taketani, H. Kohno, and R. Tokunaga, 1991, Biochem. Biophys. Res. Commun. 181, 409-415). The protein was digested with trypsin and the peptides were analyzed by reverse-phase high-performance liquid chromatography. The partial amino acid sequences of the tryptic peptides coincided with that of rat ribosomal protein P2. Immunoblot analysis and iron-binding assay confirmed that the iron-binding protein and ribosomal protein P2 are identical. Then the iron binding ability of ribosomal protein P2 was examined in rat hepatoma H4IIEC3 cells incubated with radioactive iron. When immunoprecipitation with anti-iron-binding protein serum was performed using cells incubated with 59Fe-citrate, about 4% of the 59Fe radioactivity in cells was associated with the iron-binding protein through 30 to 90 min of incubation. About 1.5% of radioactive iron in cells incubated with 59Fe-transferrin was found in immunoprecipitates with anti-iron-binding protein serum during 1 to 5 h of incubation, and 4 to 7% of the radioactivity was found in immunoprecipitates with a monoclonal antibody against ribosomal P proteins in the same incubation. These results demonstrate that ribosomal proteins P2 binds iron taken up by the cells.
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PMID:Ribosomal protein P2, a novel iron-binding protein. 152 26

The primary structure of rat liver ribosomal protein P2 was deduced from the sequence of the peptides. Ten peptides were obtained by cleavage of P2 with trypsin. The peptides, which accounted for the 111 residues of P2, were isolated by high voltage electrophoresis and chromatography on cellulose thin layer sheets, and the partial or complete sequence was determined by micromanual or solid-phase procedures using 4-N,N-dimethylaminoazobenzene 4'-isothiocyanate and phenylisothiocyanate. In a similar manner, the sequence of 14 peptic peptides was determined. The sequence of the NH2-terminal 30 residues of P2 was obtained by automatic Edman degradation in a sequenator. The ordering of the tryptic peptides was aided by determination of the partial or complete sequence of fragments generated with chymotrypsin, or Armillaria mellea protease, or by secondary cleavage of peptic peptides with trypsin. The carboxyl-terminal sequence was obtained from a cyanogen bromide fragment and from hydrolysis with carboxypeptidase. The sequence of protein P3 was also determined. P3 differs from P2 only in that it lacks the carboxyl-terminal 8 residues, and hence, it is likely to be a proteolytic product of P2. Rat liver ribosomal protein P2 is homologous with yeast YP A1, with Artemia salina eL12, and with Halobacterium cutirubrum L20. It is likely that rat liver P2 is also homologous with the prokaryotic ribosomal "A" proteins, Escherichia coli L7/L12, Micrococcus lysodeikticus MA1, and Bacillus subtilis L9, but that during evolution, a transposition of a portion of the molecule occurred.
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PMID:The primary structure of the acidic phosphoprotein P2 from rat liver 60 S ribosomal subunits. Comparison with ribosomal 'A' proteins from other species. 709 59

The ribosomal protein P2 of Plasmodium falciparum, (PfP2), performs certain unique extra-ribosomal functions. During the few hours of cell-division, PfP2 protein moves to the external surface of the infected erythrocytes (IE) as an SDS-resistant oligomer, and at that stage treatment with specific anti- PfP2 antibodies results in an arrest of the parasite cell-division. Amongst the oligomeric forms of PfP2, mainly the homo-tetramer is peripherally anchored on the external surface of the IE. To study the anchoring of PfP2 tetramer on IE-surface, we have explored the binding properties of PfP2 protein. Using NMR and erythrocyte pull-down studies, here we report that the homo-tetrameric PfP2 protein interacted specifically with erythrocytes and not leukocytes. The hydrophobic N-terminal 72 amino acid region is the major interacting domain. The binding of P2 to RBCs was neuraminidase resistant, but trypsin sensitive. The RBC binding was exclusive to the Plasmodium PfP2 protein as even the homologous protein of the closely related Apicomplexan parasite Toxoplasma gondii TgP2 protein did not interact with erythrocytes. Pull down assays, immunoprecipitation and mass spectrometry data showed that erythrocytic Band 3 protein is a possible interactor of Plasmodium PfP2 protein on the erythrocyte surface.
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PMID:Molecular study of binding of Plasmodium ribosomal protein P2 to erythrocytes. 3271 9