Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The brindled mouse mutant (Mo(br)) is the closest animal model of the human genetic copper deficiency, Menkes disease, which is presumed to be due to a mutation at the X-linked mottled locus (Mo). The mutant mice are hypopigmented and die at around 15 days after birth, but can be saved by treatment with copper before the 10th postnatal day. Menkes disease has been shown to be due to mutations of the gene ATP7A which encodes P-type ATPase (referred to here as MNK). MNK is likely to function in copper efflux from cells, but the full range of its biological activity is not fully understood. The nature of the mutation in the brindled mouse is of importance in our understanding of the role of MNK and for devising treatment strategies for Menkes disease. Here we show that the brindled mouse has a deletion of two amino acids in a highly conserved, but functionally uncharacterized, region of Mnk. Comparison with the Ca ATPases suggests this region may be involved in conformational changes associated with the E1/E2 transition fundamental to the action of P-type ATPases. We also describe the first Western blot data for Mnk in tissues, and these show normal levels of Mnk in mutant and brindled kidneys but none in liver. In the kidney, immunohistochemistry demonstrated Mnk in the proximal and distal tubules, the distribution is identical in mutant and normal. This distribution is consistent with Mnk being involved in copper resorption from the urine.
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PMID:Molecular basis of the brindled mouse mutant (Mo(br)): a murine model of Menkes disease. 921 72

The gene for Menkes disease, an X-linked disorder of copper transport, has recently been identified and shown to encode a copper-transporting P-type ATPase. The macular mutant mouse has been proposed as an animal model for Menkes disease. In the present study, we report the finding of a missense mutation in the mottled gene of the macular mouse. A single base change, T to C, at nucleotide position 4223, is predicted to result in an amino acid change from serine to proline at residue 1382 in the eighth transmembrane domain. This mutation differs from the 6-bp deletion we find in brindled cDNA. With validation of macular as an animal model of Menkes disease, we compared mottled gene expression in the intestine, kidney, and brain of macular and normal mice. In Northern analyses an 8.3-kb transcript was detected in the intestine, kidney, and brain of both normal and macular mice, with the level of transcript in macular approximately 80% that of normal. In situ hybridization studies revealed that the mottled gene was clearly expressed in intestinal epithelial cells, Paneth cells, and renal proximal tubular cells of both normal and macular mice. In normal brain, mottled gene expression was most intensely observed in the choroid plexus, in Ammon's born and the dentate gyrus in the hippocampus, in Purkinje cells, and the granular layer of the cerebellum. The intensity and localization of the signals in the brain of macular mice were similar to those of the controls. The distribution of expression of mottled is correlated with cells and tissues showing histopathology or abnormal copper sequestration in macular and other mutants.
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PMID:Mutation analysis and expression of the mottled gene in the macular mouse model of Menkes disease. 938 Apr 33

Menkes disease is an X-linked disorder in copper transport that results in death during early childhood. The solution structures of both apo and Ag(I)-bound forms of the fourth metal-binding domain (mbd4) from the Menkes copper-transporting ATPase have been solved. The 72-residue mbd4 has a ferredoxin-like beta alpha beta beta alpha beta fold. Structural differences between the two forms are limited to the metal-binding loop, which is disordered in the apo structure but well ordered in the Ag(I)-bound structure. Ag(I) binds in a linear bicoordinate manner to the two Cys residues of the conserved GMTCxxC motif; Cu(I) likely coordinates in a similar manner. Menkes mbd4 is thus the first bicoordinate copper-binding protein to be characterized structurally. Sequence comparisons with other heavy-metal-binding domains reveal a conserved hydrophobic core and metal-binding motif.
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PMID:Solution structure of the fourth metal-binding domain from the Menkes copper-transporting ATPase. 943 18

The ATP7A gene encodes a copper-transporting ATPase. Mutations in this gene result in two clinically distinct X-linked inherited disorders: Menkes disease and occipital horn syndrome (OHS). We identified a single exon skipping in the ATP7A transcript in cells from the affected proband, affected cousins and obligate carriers in a family with OHS. Genomic sequencing identified an A-->T transversion at the +3 position in the splice donor site of intron 10 (gtaaagt-->gttaagt) in all affected individuals and the obligate female carriers. This mutation results in the constitutive skipping of exon 10 and creates an in-frame deletion of transmembrane domains 3 and 4 (78 amino acids) in the mature transcript. The exon 10-skipped transcript is present in low amounts as an alternatively spliced product in normal individuals. Immunocytochemical assay shows that these two protein products have different subcellular distributions: the major form is concentrated in the perinuclear Golgi system while the minor form (as the only form in this family with OHS) is co-localized with the endoplasmic reticulum-resident BiP protein (GRP78). These findings indicate that endoplasmic reticulum localization only of a variant ATP7A protein is insufficient to effect normal copper transport.
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PMID:Constitutive skipping of alternatively spliced exon 10 in the ATP7A gene abolishes Golgi localization of the menkes protein and produces the occipital horn syndrome. 946 5

Menkes syndrome is an X-linked genetic copper deficiency that is usually fatal in early childhood. Milder variants exist, including occipital horn syndrome, which is primarily a connective tissue disorder. Mutations of the mottled locus in mice produce a wide range of copper-deficient phenotypes that are good models for human diseases. Understanding the nature of the defects has been greatly increased as a result of the identification of the gene affected in Menkes syndrome. The gene spans approximately 140 kilobases, contains 23 exons, and encodes a copper-transporting ATPase termed MNK that is thought to be involved in copper efflux from cells. More recent studies show that MNK is located primarily in the trans-Golgi compartment of Chinese hamster ovary cells. Copper-resistant cells overexpress MNK and can efflux more copper than parental cells, consistent with the copper efflux role proposed for MNK. Patients with Menkes syndrome are predicted to have little or no MNK activity, whereas patients with occipital horn syndrome have less severe mutations and some residual MNK activity is predicted. Similarly, the mottled mice mutants have a range of mutations in the MNK gene homologue. Complete loss of MNK, however, produces a fetal lethal phenotype in mice. A model is proposed to explain the wide range of phenotypes exhibited by the different mouse mutants. Further research into the cell biology of copper transport is expected to reveal more about the molecular basis of copper homeostasis.
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PMID:Menkes syndrome and animal models. 958 46

Menkes' disease is a fatal, X-linked, copper deficiency disorder that results from defective copper efflux from intestinal cells and inadequate copper delivery to other tissues, leading to deficiencies of critical copper-dependent enzymes. Wilson's disease is an autosomally inherited, copper toxicosis disorder resulting from defective biliary excretion of copper, which leads to copper accumulation in the liver. The ATP7A and ATP7B genes that are defective in patients with Menkes' and Wilson's diseases, respectively, encode transmembrane, P-type ATPase proteins (ATP7A or MNK and ATP7B or WND, respectively) that function to translocate copper across cellular membranes. In this study, the cDNAs derived from a normal human ATP7A gene and the murine ATP7B homologue, Atp7b, were separately transfected into an immortalized fibroblast cell line obtained from a Menkes' disease patient. Both MNK and WND expressed from plasmid constructs were able to correct the copper accumulation and copper retention phenotype of these cells. However, the two proteins responded differently to elevated extracellular copper levels. Although MNK showed copper-induced trafficking from the trans-Golgi network to the plasma membrane, in the same cell line the intracellular location of WND did not appear to be affected by elevated copper.
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PMID:Correction of the copper transport defect of Menkes patient fibroblasts by expression of the Menkes and Wilson ATPases. 981 47

Wiskott-Aldrich syndrome (WAS) is an X-linked immunodeficiency disorder associated with lymphocytes and platelet abnormalities. The gene that encodes the Wiskott-Aldrich protein (WASP) was recently isolated, and shown to be defective in WAS patients. WASP contains multiple domains that interact with various signalling proteins, including the guanine triphosphatase (GTPase) Cdc42Hs and SH3 domain-containing proteins. Biochemical and genetic evidence strongly suggests that WASP is an important protein in the regulation of cell morphology. Recent progress in the identification of molecular partners for WASP suggests a molecular mechanism for the cellular abnormalities of WAS.
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PMID:Understanding the molecular basis of Wiskott-Aldrich syndrome. 981 92

The group of X-linked mottled (Atp7aMo) mutations in mice is described. A normal gene encodes a copper-binding P-type ATPase. Mutant animals have the disturbance in copper metabolism, hemizygous males (Mo/y) die between 14-18 days of life, heterozygous females (Mo/+) are normal and fertile. This kind of copper metabolic defect is observed also in other animal and in human. In human Menkes disease caused by X-linked Atp7a mutant gene leads to death in early childhood. Because of is 89% of homology between Atp7aMo gene and Atp7a locus in human, mottled mutations are an excellent model for Menkes disease.
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PMID:[Mice with mottled mutation--a model for defective copper metabolism in humans]. 985 76

Human cells express at least eight members of the MutT motif protein (or nudix hydrolase) family. These enzymes are believed to eliminate toxic nucleotide derivatives from the cell and regulate the levels of important signalling nucleotides and their metabolites. Six have been fully or partially characterized: i) hMTH1 is a nucleoside triphosphatase which restricts AT-->CG transversions by specifically degrading the oxidized nucleotide 8-oxo-dGTP; ii) hAPAH1 preferentially degrades the signalling dinucleotide Ap4A; iii) DIPP is unusual in hydrolysing two seemingly unrelated signalling substrate groups - the dinucleotides Ap6A and Ap5A, and the diphosphoinositol polyphosphates; iv) DIPP2 is closely related to DIPP; v) hYSAH1 is an NDP-sugar hydrolase which prefers ADP-ribose, and vi) hGFG is a protein of unknown function encoded by the antisense transcript of the basic fibroblast growth factor gene. Although not yet associated with known hereditary or acquired disorders, the functional loss of any one of these hydrolases would be expected to be detrimental to cellular function. Furthermore, the ialA invasion gene of Bartonella bacilliformis and other invasive pathogens encodes a MutT motif Ap4A hydrolase while poxviruses express two MutT motif proteins, at least one of which is essential for infectivity. This protein family, therefore, occupies a position of some importance in controlling human health and disease.
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PMID:The MutT motif family of nucleotide phosphohydrolases in man and human pathogens (review). 1037 42

Menkes disease is an X-linked disorder of copper metabolism. An overall copper deficiency reduces the activity of copper-dependent enzymes accounting for the clinical presentation of affected individuals. The Menkes gene product (MNK) is a P-type ATPase and is considered to be the main copper efflux protein in most cells. The protein is located primarily at the trans -Golgi network (TGN), but relocalizes to the plasma membrane in elevated copper conditions to expel the excess copper from the cell. Here we report the first missense mutation which causes mild Menkes disease, a mutation in a successfully copper-treated classical Menkes patient and the effect of each mutation on the localization of MNK within the cell. Using western blot analysis, MNK was detectable in cells from both patients, but appeared to be mislocalized in the treated case. In the mild Menkes patient, the protein appeared to be located in the TGN but failed to redistribute towards the cell periphery in response to copper. This is the first description of a mutation in a Menkes patient which affects the trafficking of MNK, and the loss of this process is consistent with the clinical phenotype.
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PMID:Defective copper-induced trafficking and localization of the Menkes protein in patients with mild and copper-treated classical Menkes disease. 1040 Oct 4


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