Interacting selectively and non-covalently with the oxidized form, FAD, of flavin-adenine dinucleotide, the coenzyme or the prosthetic group of various flavoprotein oxidoreductase enzymes.
The mitochondrial amidoxime reducing component mARC is a newly discovered molybdenum enzyme that is presumed to form the catalytical part of a three-component enzyme system, consisting of mARC, heme/cytochrome b(5), and NADH/FAD-dependent cytochrome b(5) reductase. mARC proteins share a significant degree of homology to the molybdenum cofactor-binding domain of eukaryotic molybdenum cofactor sulfurase proteins, the latter catalyzing the post-translational activation of aldehyde oxidase and xanthine oxidoreductase. The human genome harbors two mARC genes, referred to as hmARC-1/MOSC-1 and hmARC-2/MOSC-2, which are organized in a tandem arrangement on chromosome 1. Recombinant expression of hmARC-1 and hmARC-2 proteins in Escherichia coli reveals that both proteins are monomeric in their active forms, which is in contrast to all other eukaryotic molybdenum enzymes that act as homo- or heterodimers. Both hmARC-1 and hmARC-2 catalyze the N-reduction of a variety of N-hydroxylated substrates such as N-hydroxy-cytosine, albeit with different specificities. Reconstitution of active molybdenum cofactor onto recombinant hmARC-1 and hmARC-2 proteins in the absence of sulfur indicates that mARC proteins do not belong to the xanthine oxidase family of molybdenum enzymes. Moreover, they also appear to be different from the sulfite oxidase family, because no cysteine residue could be identified as a putative ligand of the molybdenum atom. This suggests that the hmARC proteins and sulfurase represent members of a new family of molybdenum enzymes.
Interacting selectively and non-covalently with FAD, flavin-adenine dinucleotide, the coenzyme or the prosthetic group of various flavoprotein oxidoreductase enzymes, in either the oxidized form, FAD, or the reduced form, FADH2.
Interacting selectively and non-covalently with nicotinamide adenine dinucleotide, a coenzyme involved in many redox and biosynthetic reactions; binding may be to either the oxidized form, NAD+, or the reduced form, NADH.
J. Biol. Chem. 267, 20416-20421 (1992)[PubMed:1400360]
Nucleotide substitutions in the gene for NADH-cytochrome b5 reductase were identified in three independent probands of hereditary methemoglobinemia type I. Patients in Kagoshima and Okinawa in Japan were shown to possess the same base change, from guanine to adenine at codon 57, which results in amino acid substitution from Arg to Gln. This nucleotide change was the same as formerly found in a patient in Toyoake, Japan (Katsube, T., Sakamoto, N., Kobayashi, Y., Seki, R., Hirano, M., Tanishima, K., Tomoda, A., Takazakura, E., Yubisui, T., Takeshita, M., Sakaki, Y., and Fukumaki, Y. (1991) Am. J. Hum. Genet. 48, 799-808). A type I patient in Italy was shown to have a base change from guanine to adenine at codon 105 which causes substitution from Val to Met. To characterize the enzymes of type I patients, Arg-57----Gln and Val-105----Met mutant enzymes were overexpressed in Escherichia coli and purified to homogeneity. kcat/Km values (NADH) of these two enzymes were 25% in Arg-57----Gln and 14.5% in Val-105----Met compared with that of the wild type enzyme, while the value of type II (generalized, severe form of the disease) mutant enzyme was 3% of the normal value (Yubisui, T., Shirabe, K., Takeshita, M., Kobayashi, Y., Fukumaki, Y., Sakaki, Y., and Takano, T. (1991) J. Biol. Chem. 266, 66-70). The type I mutant enzymes were less heat-stable and more susceptible to proteinase treatment than the wild type. From these results we conclude that restriction of enzyme deficiency to red cells in hereditary methemoglobinemia type I may be generally derived from instability and increased proteolytic susceptibility of variant NADH-cytochrome b5 reductases due to a point mutation.
The chemical reactions and pathways resulting in the formation of cholesterol, cholest-5-en-3 beta-ol, the principal sterol of vertebrates and the precursor of many steroids, including bile acids and steroid hormones.
IEAUniProtKB KW
Enzymatic activity
This protein acts as an enzyme. It is known to catalyze the following reaction
Protein involved in the synthesis of cholesterol, the major sterol of higher animals. It is a component of cell membranes, especially of the plasma membrane.
Protein which participates in the biochemical reactions where cholesterol is involved, including transport. Cholesterol is the major sterol of higher animals and an important component of cell membranes, especially of the plasma membrane.
Protein involved in the synthesis of lipids, a diverse class of compounds which are insoluble in water but soluble in organic solvents. They include fats, oils, triacylglycerols, fatty acids, glycolipids, phospholipids and steroids.
Protein involved in the biochemical reactions of lipids. Lipids are a diverse class of compounds which are insoluble in water but soluble in organic solvents. They include fats, oils, triacylglycerols, fatty acids, glycolipids, phospholipids and steroids.
In vivo synthesis of steroids (steroidogenesis), a large group of complex polycyclic lipids that consist of a 17-carbon ring system. Examples are bile acids, sterols, various hormones and saponins.
Protein involved in the biochemical reactions of steroids. Steroids are a large group of complex tetracyclic lipids that consist of a 17- carbon-ring system. Examples are bile acids, sterols, various hormones and saponins.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.