Abstract
Ribulosamines, which are substrates for the deglycating enzyme fructosamine-3-kinase-related protein, are presumably formed intracellularly through glycation of proteins with ribose 5-phosphate followed by dephosphorylation of resulting RN5Ps (ribulosamine 5-phosphates) by a putative RN5Pase (ribulosamine-5-phosphatase). Ribose 5-phosphate is known to be a potent glycating agent and we show in the present study that it reacts approximately 10 and 80-fold more rapidly with protein than ribose and glucose respectively. We also show that tissue extracts and, most particularly, erythrocyte extracts contain a protein-RN5Pase. We have purified this enzyme from human erythrocytes to near homogeneity and shown it to correspond to LMWPTP-A [low-molecular-mass ('weight') protein tyrosine phosphatase-A]. Human recombinant LMWPTP-A displayed an RN5Pase activity that was higher than its tyrosine phosphatase activity, indicating that this phosphatase may participate in protein deglycation, a new form of protein repair.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Erythrocytes / enzymology
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Glycosylation
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Humans
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Male
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Molecular Sequence Data
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Molecular Weight
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Phosphoprotein Phosphatases / chemistry
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Phosphoprotein Phosphatases / isolation & purification
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Phosphoprotein Phosphatases / metabolism*
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Phosphorylation
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Phosphotransferases (Alcohol Group Acceptor) / metabolism
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Protein Tyrosine Phosphatases / chemistry
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Protein Tyrosine Phosphatases / isolation & purification
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Protein Tyrosine Phosphatases / metabolism*
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Rats
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Rats, Wistar
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Receptor-Like Protein Tyrosine Phosphatases, Class 4
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Receptors, Cell Surface / chemistry
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Receptors, Cell Surface / isolation & purification
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Receptors, Cell Surface / metabolism*
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Ribosemonophosphates / metabolism
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Substrate Specificity
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Tissue Distribution
Substances
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Receptors, Cell Surface
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Ribosemonophosphates
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ribose-5-phosphate
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FN3KRP protein, human
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Phosphotransferases (Alcohol Group Acceptor)
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Phosphoprotein Phosphatases
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PTPRA protein, human
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Protein Tyrosine Phosphatases
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Ptpra protein, rat
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Receptor-Like Protein Tyrosine Phosphatases, Class 4