Flavoprotein pyridine nucleotide cytochrome reductase (IPR001709)

Short name: Flavoprot_Pyr_Nucl_cyt_Rdtase

Overlapping homologous superfamilies

Domain relationships


Flavoprotein pyridine nucleotide cytochrome reductases [PMID: 1748631] (FPNCR) catalyse the interchange of reducing equivalents between one-electron carriers and the two-electron-carrying nicotinamide dinucleotides. The enzymes include ferredoxin:NADP+reductases (FNR) [PMID: 8027025], plant and fungal NAD(P)H:nitrate reductases [PMID: 1748631, PMID: 2204158], NADH:cytochrome b5 reductases [PMID: 3700359], NADPH:P450 reductases [PMID: 1908607], NADPH:sulphite reductases [PMID: 2550423], nitric oxide synthases [PMID: 1712077], phthalate dioxygenase reductase [PMID: 8298460], and various other flavoproteins.

Despite functional similarities, FPNCRs show no sequence similarity to NADPH:adrenodoxin reductases [PMID: 2924777], nor to bacterial ferredoxin:NAD+reductases and their homologues [PMID: 2319593]. To date, 3D-structures of 4 members of the family have been solved: Spinacia oleracea (Spinach) ferredoxin:NADP+ reductase [PMID: 1986412]; Burkholderia cepacia (Pseudomonas cepacia) phthalate dioxygenase reductase [PMID: 8298460]; the flavoprotein domain of Zea mays (Maize) nitrate reductase [PMID: 7812715]; and Sus scrofa (Pig) NADH:cytochrome b5 reductase [PMID: 7890048]. In all of them, the FAD-binding domain (N-terminal) has the topology of an anti-parallel beta-barrel, while the NAD(P)-binding domain (C-terminal) has the topology of a classical pyridine dinucleotide-binding fold (i.e. a central parallel beta-sheet with 2 helices on each side) [PMID: 8298460]. In spite of such structural similarities, the level of amino acid identity between family members is at or below the limit of significance (e.g., nitrate reductase is only 15% identical to FNR) [PMID: 7812715].

GO terms

Biological Process

GO:0055114 oxidation-reduction process

Molecular Function

GO:0016491 oxidoreductase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.