An iron-regulated ferric reductase associated with the absorption of dietary iron.
The ability of intestinal mucosa to absorb dietary ferric iron is attributed to the presence of a brush-border membrane reductase activity that displays adaptive responses to iron status. We have isolated a complementary DNA, Dcytb (for duodenal cytochrome b), which encoded a putative plasma membrane di-heme protein in mouse duodenal mucosa. Dcytb shared between 45 and 50% similarity to the cytochrome b561 family of plasma membrane reductases, was highly expressed in the brush-border membrane of duodenal enterocytes, and induced ferric reductase activity when expressed in Xenopus oocytes and cultured cells. Duodenal expression levels of Dcytb messenger RNA and protein were regulated by changes in physiological modulators of iron absorption. Thus, Dcytb provides an important element in the iron absorption pathway.
Department of Molecular Medicine, Guy's, King's and St. Thomas' School of Medicine, King's College London, Rayne Institute, Denmark Hill Campus, 123 Coldharbour Lane, London SE5 9NU, UK. andrew.t.mckie@kcl.ac.uk
A T
AT
McKie
D
D
Barrow
G O
GO
Latunde-Dada
A
A
Rolfs
G
G
Sager
E
E
Mudaly
M
M
Mudaly
C
C
Richardson
D
D
Barlow
A
A
Bomford
T J
TJ
Peters
K B
KB
Raja
S
S
Shirali
M A
MA
Hediger
F
F
Farzaneh
R J
RJ
Simpson
D000595:Amino Acid Sequence; D000740:Anemia / Q000201:enzymology; D000818:Animals; D002460:Cell Line; D003001:Cloning, Molecular; D003573:Cytochrome b Group / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary; D004386:Duodenum / Q000201:enzymology / Q000378:metabolism*; D020895:Enterocytes / Q000201:enzymology / Q000378:metabolism; D004790:Enzyme Induction; D005290:Ferric Compounds / Q000378:metabolism*; D000860:Hypoxia; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000201:enzymology / Q000378:metabolism*; D019266:Iron, Dietary / Q000008:administration & dosage / Q000378:metabolism*; D008297:Male; D051379:Mice; D008871:Microvilli / Q000201:enzymology / Q000378:metabolism; D008969:Molecular Sequence Data; D009580:Nitroblue Tetrazolium / Q000378:metabolism; D009865:Oocytes; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013778:Tetrazolium Salts / Q000378:metabolism; D013844:Thiazoles / Q000378:metabolism; D014162:Transfection; D015854:Up-Regulation; D014981:Xenopus
D003573:Cytochrome b Group; D018076:DNA, Complementary; D005290:Ferric Compounds; D019266:Iron, Dietary; D012333:RNA, Messenger; D013778:Tetrazolium Salts; D013844:Thiazoles; C023646:cytochrome b561; D009580:Nitroblue Tetrazolium; D010088:Oxidoreductases; C498909:Cybrd1 protein, mouse; C022616:thiazolyl blue