Functional analysis of the N-terminal CXXC metal-binding motifs in the human Menkes copper-transporting P-type ATPase expressed in cultured mammalian cells

The Menkes protein (MNK) is a copper-transporting P-type ATPase, which has six highly conserved metal-binding sites, GMTCXXC, at the N terminus. The metal-binding sites may be involved in MNK trafficking and/or copper- translocating activity. In this study, we report the detailed functional analysis in mammalian cells of recombinant human MNK and its mutants with various metal-binding sites altered by site-directed mutagenesis. The results of the study, both in vitro and in vivo, provide evidence that the metal- binding sites of MNK are not essential for the ATP-dependent copper- translocating activity of MNK. Moreover, metal-binding site mutations, which resulted in a loss of ability of MNK to traffick to the plasma membrane, produced a copper hyperaccumulating phenotype. Using an in vitro vesicle assay, we demonstrated that the apparent K(m) and V(max) values for the wild type MNK and its mutants were not significantly different. The results of this study suggest that copper-translocating activity of MNK and its copper- induced relocalization to the plasma membrane represent a well coordinated copper homeostasis system. It is proposed that mutations in MNK which alter either its catalytic activity or/and ability to traffick can be the cause of Menkes disease

Erratum: Functional analysis of the N-terminal CXXC metal-binding motifs in the human Menkes copper-transporting P-type ATPase expressed in cultured mammalian cells (Journal of Biological Chemistry (1999) 274 (22008-22012))

Erratum: Functional analysis of the N-terminal CXXC metal-binding motifs in the human Menkes copper-transporting P-type ATPase expressed in cultured mammalian cells (Journal of Biological Chemistry (1999) 274 (22008-22012)

Insights from using an outcomes measurement properties search filter and conducting citation searches to locate psychometric articles of tools used to measure context attributes

Objectives: To describe our experience with using a methodological outcomes measurement search filter (precise and sensitive versions of a filter designed to locate articles that report on psychometric properties of measurement tools) and citation searches to locate psychometric articles for tools that can be used to measure context attributes. To compare the precise filter when used alone and with reference list checking to citation searching according to number of records found, precision, and sensitivity. Results: Using the precise filter, we located 130 of 150 (86.6%) psychometric articles related to 22 of 31 (71.0%) tools that potentially measured an attribute of context. In a subset of six tools, the precise filter alone was more precise than searching with the precise filter combined with reference list searching, or citation searching alone. The precise filter combined with reference list checking was the most sensitive search method examined. Overall, we found the precise filter helpful for our project as it decreased record screening time. For non-patient reported outcomes tools, we had less success with locating psychometric articles using the precise filter because some psychometric articles were not indexed in PubMed. More research that systematically evaluates database searching methods is needed to validate our findings