Solution structure of apoWLN5-6
[ATP7B_HUMAN] Defects in ATP7B are the cause of Wilson disease (WD) [MIM:277900]. WD is an autosomal recessive disorder of copper metabolism in which copper cannot be incorporated into ceruloplasmin in liver, and cannot be excreted from the liver into the bile. Copper accumulates in the liver and subsequently in the brain and kidney. The disease is characterized by neurologic manifestations and signs of cirrhosis.                                                  
[ATP7B_HUMAN] Involved in the export of copper out of the cells, such as the efflux of hepatic copper into the bile.
Publication Abstract from PubMed
Human Wilson protein is a copper-transporting ATPase located in the secretory pathway possessing six N-terminal metal-binding domains. Here we focus on the function of the metal-binding domains closest to the vesicular portion of the copper pump, i.e., domain 4 (WLN4), and a construct of domains 5 and 6 (WLN5-6). For comparison purposes, some experiments were also performed with domain 2 (WLN2). The solution structure of apoWLN5-6 consists of two ferredoxin folds connected by a short linker, and (15)N relaxation rate measurements show that it behaves as a unit in solution. An NMR titration of apoWLN5-6 with the metallochaperone Cu(I)HAH1 reveals no complex formation and no copper exchange between the two proteins, whereas titration of Cu(I)HAH1 with WLN4 shows the formation of an adduct that is in fast exchange on the NMR time scale with the isolated protein species as confirmed by (15)N relaxation data. A similar interaction is also observed between Cu(I)HAH1 and WLN2; however, the relative amount of the adduct in the protein mixture is lower. An NMR titration of apoWLN5-6 with Cu(I)WLN4 shows copper transfer, first to WLN6 then to WLN5, without the formation of an adduct. Therefore, we suggest that WLN4 and WLN2 are two acceptors of Cu(I) from HAH1, which then somehow route copper to WLN5-6, before the ATP-driven transport of copper across the vesicular membrane.
Structure of human Wilson protein domains 5 and 6 and their interplay with domain 4 and the copper chaperone HAH1 in copper uptake.,Achila D, Banci L, Bertini I, Bunce J, Ciofi-Baffoni S, Huffman DL Proc Natl Acad Sci U S A. 2006 Apr 11;103(15):5729-34. Epub 2006 Mar 29. PMID:16571664
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.