Identification of zyklopen, a new member of the vertebrate multicopper ferroxidase family, and characterization in rodents and human cells.
We previously detected a membrane-bound, copper-containing oxidase that may be involved in iron efflux in BeWo cells, a human placental cell line. We have now identified a gene encoding a predicted multicopper ferroxidase (MCF) with a putative C-terminal membrane-spanning sequence and high sequence identity to hephaestin (Heph) and ceruloplasmin (Cp), the other known vertebrate MCF. Molecular modeling revealed conservation of all type I, II, and III copper-binding sites as well as a putative iron-binding site. Protein expression was observed in multiple diverse mouse tissues, including placenta and mammary gland, and the expression pattern was distinct from that of Cp and Heph. The protein possessed ferroxidase activity, and protein levels decreased in cellular copper deficiency. Knockdown with small interfering RNA in BeWo cells indicates that this gene represents the previously detected oxidase. We propose calling this new member of the MCF family "zyklopen."
Chen
Huijun
H
Department of Nutritional Science and Toxicology, University of California, Berkeley, CA 94720, USA.
Attieh
Zouhair K
ZK
Syed
Basharut A
BA
Kuo
Yien-Ming
YM
Stevens
Valerie
V
Fuqua
Brie K
BK
Andersen
Henriette S
HS
Naylor
Claire E
CE
Evans
Robert W
RW
Gambling
Lorraine
L
Danzeisen
Ruth
R
Bacouri-Haidar
Mhenia
M
Usta
Julnar
J
Vulpe
Chris D
CD
McArdle
Harry J
HJ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D018938:Caco-2 Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D002570:Ceruloplasmin / Q000032:analysis / Q000737:chemistry* / Q000235:genetics*; D003300:Copper / Q000032:analysis* / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D006801:Humans; D007501:Iron / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000201:enzymology; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008813:Mice, Inbred ICR; D008958:Models, Molecular; D009928:Organ Specificity; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry; D010920:Placenta / Q000201:enzymology; D011247:Pregnancy; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D017385:Sequence Homology
C492164:HEPH protein, human; C117324:Heph protein, mouse; C492163:Heph, protein, rat; D008565:Membrane Proteins; D010446:Peptide Fragments; D034741:RNA, Small Interfering; D003300:Copper; D007501:Iron; D002570:Ceruloplasmin; C022345:4-phenylenediamine oxidase; D000587:Oxidoreductases Acting on CH-NH Group Donors