Identification and functional expression of HAH1, a novel human gene involved in copper homeostasis.
To search for a mammalian homologue of ATX1, a human liver cDNA library was screened and a cDNA clone was isolated, which encodes a protein with 47% amino acid identity to Atx1p including conservation of the MTCXGC copper-binding domain. RNA blot analysis using this cDNA identified an abundant 0.5-kilobase mRNA in all human tissues and cell lines examined. Southern blot analysis using this same clone indicated that the corresponding gene exists as a single copy in the haploid genome, and chromosomal localization by fluorescence in situ hybridization detected this locus at the interface between bands 5q32 and 5q33. Yeast strains lacking copper/zinc superoxide dismutase (SOD1) are sensitive to redox cycling agents and dioxygen and are auxotrophic for lysine when grown in air, and expression of this human ATX1 homologue (HAH1) in these strains restored growth on lysine-deficient media. Yeast strains lacking ATX1 are deficient in high affinity iron uptake and expression of HAH1 in these strains permits growth on iron-depleted media and results in restoration of copper incorporation into newly synthesized Fet3p. These results identify HAH1 as a novel ubiquitously expressed protein, which may play an essential role in antioxidant defense and copper homeostasis in humans.
Klomp
L W
LW
Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Lin
S J
SJ
Yuan
D S
DS
Klausner
R D
RD
Culotta
V C
VC
Gitlin
J D
JD
D000595:Amino Acid Sequence; D001483:Base Sequence; D015139:Blotting, Southern; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D027682:Cation Transport Proteins; D002871:Chromosome Banding; D003300:Copper / Q000502:physiology*; D000079922:Copper Transport Proteins; D005656:Fungal Proteins / Q000737:chemistry*; D015723:Gene Library; D005816:Genetic Complementation Test; D006706:Homeostasis; D006801:Humans; D008099:Liver / Q000737:chemistry; D056511:Metallochaperones; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D029701:Saccharomyces cerevisiae Proteins
C474500:ATOX1 protein, human; C093341:ATX1 protein, S cerevisiae; D002352:Carrier Proteins; D027682:Cation Transport Proteins; D000079922:Copper Transport Proteins; D005656:Fungal Proteins; D056511:Metallochaperones; D018832:Molecular Chaperones; D029701:Saccharomyces cerevisiae Proteins; D003300:Copper