2h2u

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2h2u, resolution 2.40Å ()
Ligands:
Gene: CANT1, SHAPY (Homo sapiens)
Activity: Nucleoside-diphosphatase, with EC number 3.6.1.6
Related: 2h2n, 1s18, 1s1d
Resources: FirstGlance, OCA, RCSB, PDBsum
Coordinates: save as pdb, mmCIF, xml



Crystal structure of the E130Y mutant of human soluble calcium-activated nucleotidase (SCAN) with calcium ion

Publication Abstract from PubMed

Mammals express a protein homologous to soluble nucleotidases used by blood-sucking insects to inhibit host blood clotting. These vertebrate nucleotidases may play a role in protein glycosylation. The activity of this enzyme family is strictly dependent on calcium, which induces a conformational change in the secreted, soluble human nucleotidase. The crystal structure of this human enzyme was recently solved; however, the mechanism of calcium activation and the basis for the calcium-induced changes remain unclear. In this study, using analytical ultracentrifugation and chemical cross-linking, we show that calcium or strontium induce noncovalent dimerization of the soluble human enzyme. The location and nature of the dimer interface was elucidated using a combination of site-directed mutagenesis and chemical cross-linking, coupled with crystallographic analyses. Replacement of Ile(170), Ser(172), and Ser(226) with cysteine residues resulted in calcium-dependent, sulfhydryl-specific intermolecular cross-linking, which was not observed after cysteine introduction at other surface locations. Analysis of a super-active mutant, E130Y, revealed that this mutant dimerized more readily than the wild-type enzyme. The crystal structure of the E130Y mutant revealed that the mutated residue is found in the dimer interface. In addition, expression of the full-length nucleotidase revealed that this membrane-bound form can also dimerize and that these dimers are stabilized by spontaneous oxidative cross-linking of Cys(30), located between the single transmembrane helix and the start of the soluble sequence. Thus, calcium-mediated dimerization may also represent a mechanism for regulation of the activity of this nucleotidase in the physiological setting of the endoplasmic reticulum or Golgi.

Calcium-dependent dimerization of human soluble calcium activated nucleotidase: characterization of the dimer interface., Yang M, Horii K, Herr AB, Kirley TL, J Biol Chem. 2006 Sep 22;281(38):28307-17. Epub 2006 Jul 11. PMID:16835225

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

About this Structure

2H2U is a 2 chains structure of sequences from Homo sapiens. Full crystallographic information is available from OCA.

Reference

  • Yang M, Horii K, Herr AB, Kirley TL. Calcium-dependent dimerization of human soluble calcium activated nucleotidase: characterization of the dimer interface. J Biol Chem. 2006 Sep 22;281(38):28307-17. Epub 2006 Jul 11. PMID:16835225 doi:10.1074/jbc.M604413200

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