Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.5.1.3 (dihydrofolate reductase)
 5,819 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The subcellular distributions of folate and folate-synthesizing enzymes were investigated in pea leaves. It was observed that the mitochondrial folate pool (approximately 400 micron) represented approximately 50% of the total pool. Furthermore, all the enzymes involved in tetrahydrofolate polyglutamate synthesis were present in the mitochondria. In marked contrast, we failed to detect any significant activity of these enzymes in chloroplasts, cytosol, and nuclei. The presence of the tetrahydrofolate synthesis pathway in mitochondria is apparently a general feature in plants since potato tuber mitochondria also contained a high folate concentration (approximately 200 micron) and all the enzymes required for tetrahydrofolate polyglutamate synthesis. The specific activities of tetrahydrofolate-synthesizing enzymes were rather low (1.5-15 nmol h-1 mg-1 matrix protein), except for dihydrofolate reductase (180-500 nmol h-1 mg-1 matrix protein). Dihydrofolate reductase was purified to homogeneity. The enzyme had a native molecular mass of approximately 140 kDa and was constituted of two identical 62-kDa subunits. Interestingly, this mitochondrial protein appeared to be a bifunctional enzyme, also supporting thymidylate synthesis. The cell distribution of thymidylate synthase was also investigated. No significant activity was observed in cell fractions other than mitochondria, indicating that plant cell mitochondria are also a major site for thymidylate synthesis.
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PMID:Mitochondria are a major site for folate and thymidylate synthesis in plants. 862 17

The cytosolic domain of the human mitochondrial protein import receptor, hTom20, has been expressed as a fusion protein with glutathione S-transferase (GST) in bacteria and the purified protein immobilized on Sepharose beads. To discriminate between specific binding of precursor proteins with the receptor and non-specific binding, precursors were recovered as a complex with GST-hTom20 following competitive elution from the beads with reduced glutathione. Here, we describe the specificity of this assay and demonstrate that the cytosolic domain of hTom20 interacts directly with the transcription-translation product of precursor proteins that bear a diverse array of targeting signals. Such proteins include a matrix protein (pODHFR), a polytopic integral protein of the inner membrane (uncoupling protein), a beta-barrel protein of the outer membrane (VDAC/porin) as well as bitopic integral proteins which are inserted into the outer membrane by either an NH2-terminal or COOH-terminal signal anchor sequence (yTom70(1-29)DHFR and Bcl-2, respectively).
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PMID:Human mitochondrial import receptor, Tom20p. Use of glutathione to reveal specific interactions between Tom20-glutathione S-transferase and mitochondrial precursor proteins. 911 86