Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fructosamine-3-kinase (FN3K) is an enzyme that appears to be responsible for the removal of fructosamines from proteins. In this study, we report the sequence of human and mouse cDNAs encoding proteins sharing 65% sequence identity with FN3K. The genes encoding FN3K and FN3K-related protein (FN3K-RP) are present next to each other on human chromosome 17q25, and they both have a similar 6-exon structure. Northern blots of mouse tissues RNAs indicate a high level of expression of both genes in bone marrow, brain, kidneys, and spleen. Human FN3K-RP was transfected in human embryonic kidney (HEK) cells, and the expressed protein was partially purified by chromatography on Blue Sepharose. Unlike FN3K, FN3K-RP did not phosphorylate fructoselysine, 1-deoxy-1-morpholino-fructose, or lysozyme glycated with glucose. In a more systematic screening for potential substrates for FN3K-RP, we found, however, that both enzymes phosphorylated ketosamines with a D-configuration in C3 (psicoselysine, 1-deoxy-1-morpholino-psicose, 1-deoxy-1-morpholino-ribulose, lysozyme glycated with allose-the C3 epimer of glucose, or with ribose). Tandem mass spectrometry and nuclear magnetic resonance analysis of the product of phosphorylation of 1-deoxy-1-morpholino-psicose by FN3K-RP indicated that this enzyme phosphorylates the third carbon of the sugar moiety. These results indicate that FN3K-RP is a ketosamine-3-kinase (ketosamine-3-kinase 2). This enzyme presumably plays a role in freeing proteins from ribulosamines or psicosamines, which might arise in a several step process, from the reaction of amines with glucose and/or glycolytic intermediates. This role is shared by fructosamine-3-kinase (ketosamine-3-kinase 1), which has, in addition, the unique capacity to phosphorylate fructosamines.
Diabetes 2003 Dec
PMID:A mammalian protein homologous to fructosamine-3-kinase is a ketosamine-3-kinase acting on psicosamines and ribulosamines but not on fructosamines. 1463 48

Nonenzymatic glycation is believed to play a major role in the development of diabetic complications. Over the past several years we and others have shown that in cells this nonenzymatic process can be reversed by an ATP-dependent reaction catalyzed by fructosamine-3-kinase (FN3K) and possibly by its isozyme, fructosamine-3-kinase-related protein (FN3KRP). In this study we provide the first evidence that this FN3K-dependent deglycation, acting on the Amadori products, is complemented by another deglycation process operating on the very first product of nonenzymatic glycation, glucosylamines (Schiff's bases). We postulate that the first step in this Schiff's-base deglycation process occurs by transfer of the sugar moiety from macromolecule-bound glucosylamine to one of the low-molecular weight intracellular nucleophiles-in particular, glutathione. We term this reaction transglycation, and in this study we demonstrate that it occurs readily and spontaneously in vitro. We further propose that one of the spontaneously formed glucose-glutathione adduct(s) is subsequently removed from cells by a multidrug-resistance pump (MRP, MDR-protein, ATP-binding-cassette protein), metabolized, and excreted in urine. In support of this latter contention, we show that at least one transglycation product, glucose-cysteine, is found in human urine and that its concentrations are increased in diabetes.
 ...
PMID:Transglycation--a potential new mechanism for deglycation of Schiff's bases. 1603 12