3h54
From Proteopedia
Crystal Structure of human alpha-N-acetylgalactosaminidase,complex with GalNAc
Structural highlights
Disease[NAGAB_HUMAN] Defects in NAGA are the cause of Schindler disease (SCHIND) [MIM:609241]. Schindler disease is a form of NAGA deficiency characterized by early onset neuroaxonal dystrophy and neurological signs (convulsion during fever, epilepsy, psychomotor retardation and hypotonia). NAGA deficiency is typically classified in three main phenotypes: NAGA deficiency type I (Schindler disease or Schindler disease type I) with severe manifestations; NAGA deficiency type II (Kanzazi disease or Schindler disease type II) which is mild; NAGA deficiency type III (Schindler disease type III) characterized by mild-to-moderate neurologic manifestations. NAGA deficiency results in the increased urinary excretion of glycopeptides and oligosaccharides containing alpha-N-acetylgalactosaminyl moieties. Inheritance is autosomal recessive.[1] [2] Defects in NAGA are the cause of Kanzaki disease (KANZD) [MIM:609242]; also known as NAGA deficiency type II or Schindler disease type II. Kanzaki disease is an autosomal recessive disorder characterized by late onset, angiokeratoma corporis diffusum and mild intellectual impairment.[3] [4] Function[NAGAB_HUMAN] Removes terminal alpha-N-acetylgalactosamine residues from glycolipids and glycopeptides. Required for the breakdown of glycolipids.[5] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedalpha-N-acetylgalactosaminidase (alpha-NAGAL; E.C. 3.2.1.49) is a lysosomal exoglycosidase that cleaves terminal alpha-N-acetylgalactosamine residues from glycopeptides and glycolipids. In humans, a deficiency of alpha-NAGAL activity results in the lysosomal storage disorders Schindler disease and Kanzaki disease. To better understand the molecular defects in the diseases, we determined the crystal structure of human alpha-NAGAL after expressing wild-type and glycosylation-deficient glycoproteins in recombinant insect cell expression systems. We measured the enzymatic parameters of our purified wild-type and mutant enzymes, establishing their enzymatic equivalence. To investigate the binding specificity and catalytic mechanism of the human alpha-NAGAL enzyme, we determined three crystallographic complexes with different catalytic products bound in the active site of the enzyme. To better understand how individual defects in the alpha-NAGAL glycoprotein lead to Schindler disease, we analyzed the effect of disease-causing mutations on the three-dimensional structure. The 1.9 a structure of human alpha-N-acetylgalactosaminidase: The molecular basis of Schindler and Kanzaki diseases.,Clark NE, Garman SC J Mol Biol. 2009 Oct 23;393(2):435-47. Epub 2009 Aug 14. PMID:19683538[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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