@article {38578,
	title = {X-ray crystal structure of the hypothetical phosphotyrosine phosphatase MDP-1 of the haloacid dehalogenase superfamily},
	journal = {BiochemistryBiochemistry},
	volume = {43},
	year = {2004},
	note = {http://www.ncbi.nlm.nih.gov/pubmed/15461449?dopt=Abstract},
	type = {10.1021/bi0490688},
	abstract = {The haloacid dehalogenase (HAD) superfamily is comprised of structurally homologous enzymes that share several conserved sequence motifs (loops I-IV) in their active site. The majority of HAD members are phosphohydrolases and may be divided into three subclasses depending on domain organization. In classes I and II, a mobile "cap" domain reorients upon substrate binding, closing the active site to bulk solvent. Members of the third class lack this additional domain. Herein, we report the 1.9 A X-ray crystal structures of a member of the third subclass, magnesium-dependent phosphatase-1 (MDP-1) both in its unliganded form and with the product analogue, tungstate, bound to the active site. The secondary structure of MDP-1 is similar to that of the "core" domain of other type I and type II HAD members with the addition of a small, 28-amino acid insert that does not close down to exclude bulk solvent in the presence of ligand. In addition, the monomeric oligomeric state of MDP-1 does not allow the participation of a second subunit in the formation and solvent protection of the active site. The binding sites for the phosphate portion of the substrate and Mg(II) cofactor are also similar to those of other HAD members, with all previously observed contacts conserved. Unlike other subclass III HAD members, MDP-1 appears to be equally able to dephosphorylate phosphotyrosine and closed-ring phosphosugars. Modeling of possible substrates in the active site of MDP-1 reveals very few potential interactions with the substrate leaving group. The mapping of conserved residues in sequences of MDP-1 from different eukaryotic organisms reveals that they colocalize to a large region on the surface of the protein outside the active site. This observation combined with the modeling studies suggests that the target of MDP-1 is most likely a phosphotyrosine in an unknown protein rather than a small sugar-based substrate.},
	keywords = {Amino Acid Sequence, Animals, Binding Sites, Crystallography, X-Ray, HUMANS, Hydrogen-Ion Concentration, Hydrolases, Magnesium, Mice, Models, Molecular, Molecular Sequence Data, Phosphoprotein Phosphatases, Phosphotyrosine, Protein Phosphatase 1, Protein Structure, Quaternary, Protein Structure, Tertiary, sequence alignment, Solvents, Substrate Specificity},
	author = {Peisach, Ezra and J. Selengut and Dunaway-Mariano, Debra and Allen, Karen N.}
}
@article {38369,
	title = {MDP-1: A novel eukaryotic magnesium-dependent phosphatase},
	journal = {BiochemistryBiochemistry},
	volume = {39},
	year = {2000},
	note = {http://www.ncbi.nlm.nih.gov/pubmed/10889041?dopt=Abstract},
	abstract = {We report here the purification, cloning, expression, and characterization of a novel phosphatase, MDP-1. In the course of investigating the reported acid phosphatase activity of carbonic anhydrase III preparations, several discrete phosphatases were discerned. One of these, a magnesium-dependent species of 18.6 kDa, was purified to homogeneity and yielded several peptide sequences from which the parent gene was identified by database searching. Although orthologous genes were identified in fungi and plants as well as mammalian species, there was no apparent homology to any known family of phosphatases. The enzyme was expressed in Escherichia coli with a fusion tag and purified by affinity methods. The recombinant enzyme showed magnesium-dependent acid phosphatase activity comparable to the originally isolated rabbit protein. The enzyme catalyzes the rapid hydrolysis of p-nitrophenyl phosphate, ribose-5-phosphate, and phosphotyrosine. The selectivity for phosphotyrosine over phosphoserine or phosphothreonine is considerable, but the enzyme did not show activity toward five phosphotyrosine-containing peptides. None of the various substrates assayed (including various nucleotide, sugar, amino acid and peptide phosphates, phosphoinositides, and phosphodiesters) exhibited K(M) values lower than 1 mM, and many showed negligible rates of hydrolysis. The enzyme is inhibited by vanadate and fluoride but not by azide, cyanide, calcium, lithium, or tartaric acid. Chemical labeling, refolding, dialysis, and mutagenesis experiments suggest that the enzymatic mechanism is not dependent on cysteine, histidine, or nonmagnesium metal ions. In recognition of these observations, the enzyme has been given the name magnesium-dependent phosphatase-1 (MDP-1).},
	keywords = {Amino Acid Sequence, Animals, Catalysis, Cations, Chromatography, Affinity, Cloning, Molecular, Cysteine, Enzyme Inhibitors, Histidine, Hydrogen-Ion Concentration, Magnesium, Mice, Molecular Sequence Data, Phosphoprotein Phosphatases, Protein Phosphatase 1, Rabbits, Sequence Analysis, Protein, Sequence Homology, Amino Acid, Substrate Specificity},
	author = {J. Selengut and Levine, R. L.}
}
