May supply copper to copper-requiring proteins within the secretory pathway, when localized in the trans-Golgi network. Under conditions of elevated extracellular copper, it relocalized to the plasma membrane where it functions in the efflux of copper from cells.
CuratedUniProtKB
According to TCDB this is a transporter from family:
The human X-linked recessive disorder of copper metabolism, Menkes disease, is caused by a defect in the MNK ( ATP7A ) gene which encodes a transmembrane copper-transporting P-type ATPase (MNK). MNK is an important component of the mammalian copper transport pathway, and previous studies in cultured cells have localized MNK to the final compartment of the Golgi apparatus, the trans -Golgi network (TGN). At this location, MNK is predicted to supply copper to copper-dependent enzymes as they migrate through the secretory pathway. However, under conditions of elevated extracellular copper, the MNK protein undergoes a rapid relocalization to the plasma membrane where it functions in the efflux of copper from cells. In this study, three di-leucine motifs and a cluster of four acidic amino acids within the C-terminal region of MNK were investigated as candidate signals necessary for steady-state TGN localization. In vitro mutagenesis of the human MNK cDNA and immunofluorescence detection of mutant forms of MNK expressed in cultured cells demonstrated that the di-leucine, L1487L1488, was essential for localization of MNK within the TGN, but not for copper efflux. We suggest that this di-leucine motif is a putative endocytic targeting motif necessary for the retrieval of MNK from the plasma membrane to the TGN. Our data, along with the recent demonstration that the third transmembrane region of MNK functions as a TGN targeting signal, suggests that MNK localization to the TGN may be a two-step process involving TGN retention via the transmembrane region, and recycling to this compartment from the plasma membrane via the L1487L1488 motif.
The interaction between the human copper(I) chaperone, HAH1, and one of its two physiological partners, the Menkes disease protein (ATP7A), was investigated in solution using heteronuclear NMR. The study was carried out through titrations involving HAH1 and either the second or the fifth soluble domains of ATP7A (MNK2 and MNK5, respectively), in the presence of copper(I). The copper-transfer properties of MNK2 and MNK5 are similar, and differ significantly from those previously observed for the yeast homologous system. In particular, no stable adduct is formed between either of the MNK domains and HAH1. The copper(I) transfer reaction is slow on the time scale of the NMR chemical shift, and the equilibrium is significantly shifted towards the formation of copper(I)-MNK2/MNK5. The solution structures of both apo- and copper(I)-MNK5, which were not available, are also reported. The results are discussed in comparison with the data available in the literature for the interaction between HAH1 and its partners from other spectroscopic techniques.
Interacting selectively and non-covalently with any protein or protein complex (a complex of two or more proteins that may include other nonprotein molecules), in the presence of copper.
Evidence
1:
Inferred from Physical InteractionUniProtKB
J. Biol. Chem. 274, 28497-28504 (1999)[PubMed:10497213]
Wilson disease (WD) and Menkes disease (MNK) are inherited disorders of copper metabolism. The genes that mutate to give rise to these disorders encode highly homologous copper transporting ATPases. We use yeast and mammalian two-hybrid systems, along with an in vitro assay to demonstrate a specific, copper-dependent interaction between the six metal-binding domains of the WD and MNK ATPases and the cytoplasmic copper chaperone HAH1. We demonstrate that several metal-binding domains interact independently or in combination with HAH1p, although notably domains five and six of WDp do not. Alteration of either the Met or Thr residue of the HAH1p MTCXXC motif has no observable effect on the copper-dependent interaction, whereas alteration of either of the two Cys residues abolishes the interaction. Mutation of any one of the HAH1p C-terminal Lys residues (Lys(56), Lys(57), or Lys(60)) to Gly does not affect the interaction, although deletion of the 15 C-terminal residues abolishes the interaction. We show that apo-HAH1p can bind in vitro to copper-loaded WDp, suggesting reversibility of copper transfer from HAH1p to WD/MNKp. The in vitro HAH1/WDp interaction is metalospecific; HAH1 preincubated with Cu(2+) or Hg(+) but not with Zn(2+), Cd(2+), Co(2+), Ni(3+), Fe(3+), or Cr(3+) interacted with WDp. Finally, we model the protein-protein interaction and present a theoretical representation of the HAH1p.Cu.WD/MNKp complex.
Catalysis of the transfer of a solute or solutes from one side of a membrane to the other according to the reaction: ATP + H2O + Cu2+(in) -> ADP + phosphate + Cu2+(out).
Interacting selectively and non-covalently with any protein or protein complex (a complex of two or more proteins that may include other nonprotein molecules).
Evidence
1:
Inferred from Physical InteractionUniProtKB
The P-type ATPases affected in Menkes and Wilson diseases, ATP7A and ATP7B, respectively, are key copper transporters that regulate copper homeostasis. The N termini of these proteins are critical in regulating their function and activity, and contain six copper-binding motifs MxCxxC. In this study, we describe the identification of glutaredoxin (GRX1) as an interacting partner of both ATP7A and ATP7B, confirmed by yeast two-hybrid technology and by co-immunoprecipitation from mammalian cells. The interaction required the presence of copper and intact metal-binding motifs. In addition, the interaction was related to the number of metal-binding domains available. GRX1 catalyses the reduction of disulphide bridges and reverses the glutathionylation of proteins to regulate and/or protect protein activity. We propose that GRX1 is essential for ATPase function and catalyses either the reduction of intramolecular disulphide bonds or the deglutathionylation of the cysteine residues within the CxxC motifs to facilitate copper-binding for subsequent transport.
The chemical reactions and pathways resulting in the formation of ATP, adenosine 5'-triphosphate, a universally important coenzyme and enzyme regulator.
The process whose specific outcome is the progression of a blood vessel over time, from its formation to the mature structure. The blood vessel is the vasculature carrying blood.
The process whose specific outcome is the progression of the cartilage over time, from its formation to the mature structure. Cartilage is a connective tissue dominated by extracellular matrix containing collagen type II and large amounts of proteoglycan, particularly chondroitin sulfate.
The chemical reactions and pathways involving any of a group of physiologically important biogenic amines that possess a catechol (3,4-dihydroxyphenyl) nucleus and are derivatives of 3,4-dihydroxyphenylethylamine.
The Menkes protein (ATP7A) is defective in the Cu deficiency disorder Menkes disease and is an important contributor to the maintenance of physiological Cu homeostasis. To investigate more fully the role of ATP7A, transgenic mice expressing the human Menkes gene ATP7A from chicken beta-actin composite promoter (CAG) were produced. The transgenic mice expressed ATP7A in lung, heart, liver, kidney, small intestine, and brain but displayed no overt phenotype resulting from expression of the human protein. Immunohistochemical analysis revealed that ATP7A was found primarily in the cardiac muscle, smooth muscle of the lung, distal tubules of the kidney, intestinal enterocytes, and patches of hepatocytes, as well as in the hippocampus, cerebellum, and choroid plexus of the brain. In 60-day- and 300-day-old mice, Cu concentrations were reduced in most tissues, consistent with ATP7A playing a role in Cu efflux. The reduction in Cu was most pronounced in the hearts of older T22#2 females (24%), T22#2 males (18%), and T25#5 females (23%), as well as in the brains of 60-day-old T22#2 females and males (23% and 30%, respectively).
The process whose specific outcome is the progression of a neuron whose cell body is located in the central nervous system, from initial commitment of the cell to a neuronal fate, to the fully functional differentiated neuron.
The process in which neuroblasts acquire specialized structural and/or functional features that characterize the mature cerebellar Purkinje cell. Differentiation includes the processes involved in commitment of a neuroblast to a Purkinje cell fate. A Purkinje cell is an inhibitory GABAergic neuron found in the cerebellar cortex that projects to the deep cerebellar nuclei and brain stem.
Menkes disease is an X-linked recessive copper deficiency disorder caused by mutations in the ATP7A (MNK) gene. The MNK gene encodes a copper-transporting P-type ATPase, MNK, which is localized predominantly in the trans-Golgi network (TGN). The MNK protein relocates to the plasma membrane in cells exposed to elevated copper where it functions in copper efflux. A role for MNK at the TGN in mammalian cells has not been demonstrated. In this study, we investigated whether the MNK protein is required for the activity of tyrosinase, a copper-dependent enzyme involved in melanogenesis that is synthesized within the secretory pathway. We demonstrate that recombinant tyrosinase expressed in immortalized Menkes fibroblast cell lines was inactive, whereas in normal fibroblasts known to express MNK protein there was substantial tyrosinase activity. Co-expression of the Menkes protein and tyrosinase from plasmid constructs in Menkes fibroblasts led to the activation of tyrosinase and melanogenesis. This MNK-dependent activation of tyrosinase was impaired by the chelation of copper in the medium of cells and after mutation of the invariant phosphorylation site at aspartic acid residue 1044 of MNK. Collectively, these findings suggest that the MNK protein transports copper into the secretory pathway of mammalian cells to activate copper-dependent enzymes and reveal a second copper transport role for MNK in mammalian cells. These findings describe a single cell-based system that allows both the copper transport and trafficking functions of MNK to be studied. This study also contributes to our understanding of the molecular basis of pigmentation in mammalian cells.
The process in which the anatomical structures of a dendrite are generated and organized. A dendrite is a freely branching protoplasmic process of a nerve cell.
Any process that reduces or removes the toxicity of copper ion. These include transport of copper away from sensitive areas and to compartments or complexes whose purpose is sequestration of copper ion.
The chemical reactions and pathways resulting in the formation of elastin, a fibrous glycoprotein found in elastic tissues such as the walls of arteries.
The chemical reactions and pathways involving epinephrine, a hormone produced by the medulla of the adrenal glands that increases heart activity, improves the power and prolongs the action of muscles, and increases the rate and depth of breathing. It is synthesized by the methylation of norepinephrine.
A process that is carried out at the cellular level which results in the assembly, arrangement of constituent parts, or disassembly of an extracellular matrix.
The process whose specific outcome is the progression of the embryo in the uterus over time, from formation of the zygote in the oviduct, to birth. An example of this process is found in Mus musculus.
The specific movement from place to place of an organism in response to external or internal stimuli. Locomotion of a whole organism in a manner dependent upon some combination of that organism's internal state and external conditions.
The process whose specific outcome is the progression of the alveolus over time, from its formation to the mature structure. The alveolus is a sac for holding air in the lungs; formed by the terminal dilation of air passageways.
A process that is carried out at the cellular level which results in the assembly, arrangement of constituent parts, or disassembly of a mitochondrion; includes mitochondrial morphogenesis and distribution, and replication of the mitochondrial genome as well as synthesis of new mitochondrial components.
Any process that stops, prevents, or reduces the frequency, rate or extent of activity of a metalloenzyme. A metalloenzyme is any enzyme that contains metal.
The process in which the anatomical structures of a neuron projection are generated and organized. A neuron projection is any process extending from a neural cell, such as axons or dendrites.
The chemical reactions and pathways resulting in the formation of norepinephrine, a hormone secreted by the adrenal medulla, and a neurotransmitter in the sympathetic peripheral nervous system and in some tracts in the central nervous system. It is also the demethylated biosynthetic precursor of epinephrine.
The chemical reactions and pathways involving norepinephrine, a hormone secreted by the adrenal medulla, and a neurotransmitter in the sympathetic peripheral nervous system and in some tracts in the central nervous system. It is also the demethylated biosynthetic precursor of epinephrine.
Any process that activates or increases the frequency, rate or extent of oxidoreductase activity, the catalysis of an oxidation-reduction (redox) reaction, a reversible chemical reaction in which the oxidation state of an atom or atoms within a molecule is altered.
Menkes disease is an X-linked recessive copper deficiency disorder caused by mutations in the ATP7A (MNK) gene. The MNK gene encodes a copper-transporting P-type ATPase, MNK, which is localized predominantly in the trans-Golgi network (TGN). The MNK protein relocates to the plasma membrane in cells exposed to elevated copper where it functions in copper efflux. A role for MNK at the TGN in mammalian cells has not been demonstrated. In this study, we investigated whether the MNK protein is required for the activity of tyrosinase, a copper-dependent enzyme involved in melanogenesis that is synthesized within the secretory pathway. We demonstrate that recombinant tyrosinase expressed in immortalized Menkes fibroblast cell lines was inactive, whereas in normal fibroblasts known to express MNK protein there was substantial tyrosinase activity. Co-expression of the Menkes protein and tyrosinase from plasmid constructs in Menkes fibroblasts led to the activation of tyrosinase and melanogenesis. This MNK-dependent activation of tyrosinase was impaired by the chelation of copper in the medium of cells and after mutation of the invariant phosphorylation site at aspartic acid residue 1044 of MNK. Collectively, these findings suggest that the MNK protein transports copper into the secretory pathway of mammalian cells to activate copper-dependent enzymes and reveal a second copper transport role for MNK in mammalian cells. These findings describe a single cell-based system that allows both the copper transport and trafficking functions of MNK to be studied. This study also contributes to our understanding of the molecular basis of pigmentation in mammalian cells.
Any process that modulates the frequency, rate or extent of gene expression. Gene expression is the process in which a gene's coding sequence is converted into a mature gene product or products (proteins or RNA). This includes the production of an RNA transcript as well as any processing to produce a mature RNA product or an mRNA (for protein-coding genes) and the translation of that mRNA into protein. Some protein processing events may be included when they are required to form an active form of a product from an inactive precursor form.
Any process that modulates the frequency, rate or extent of the chemical reactions and pathways resulting in the phosphorylation of ADP to ATP that accompanies the oxidation of a metabolite through the operation of the respiratory chain. Oxidation of compounds establishes a proton gradient across the membrane, providing the energy for ATP synthesis.
The process that results in the movement of cytochrome c from the mitochondrial intermembrane space into the cytosol, which is part of the apoptotic signaling pathway and leads to caspase activation.
Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of an iron(III) ion stimulus.
Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a zinc ion stimulus.
The chemical reactions and pathways involving serotonin (5-hydroxytryptamine), a monoamine neurotransmitter occurring in the peripheral and central nervous systems, also having hormonal properties.
The process whose specific outcome is the progression of the skin over time, from its formation to the mature structure. The skin is the external membranous integument of an animal. In vertebrates the skin generally consists of two layers, an outer nonsensitive and nonvascular epidermis (cuticle or skarfskin) composed of cells which are constantly growing and multiplying in the deeper, and being thrown off in the superficial layers, as well as an inner vascular dermis (cutis, corium or true skin) composed mostly of connective tissue.
Protein involved in the transport of ions. Such proteins are usually transmembrane and mediate a movement of ions across cell membranes. Transport may be passive (facilitated diffusion; down the electrochemical gradient), or active (against the electrochemical gradient). Active transport requires energy which may come from light, oxidation reactions, ATP hydrolysis, or cotransport of other ions or molecules.
Protein involved in the transport of a molecule (metabolite, protein, etc), a ion or an electron across cell membranes, inside the cell or in a tissue fluid.
Enzyme which catalyzes hydrolysis reaction, i.e. the addition of the hydrogen and hydroxyl ions of water to a molecule with its consequent splitting into two or more simpler molecules.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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