Saposin

spinqualitylabelsall models Human saposin A complex with Ca+2 2dob Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Function Saposin (Sap) is a small protein which functions as activator of lipid-degrading enzymes. They act by isolating the lipid substrate from the membrane. Sap is synthesized as a precursor – prosaposin – which contain 4 SapB active domains (cleaved to saposin A,B,C and D) and 2 SapA domains which are cleaved off. See also Lipid metabolism. Saposin A and C stimulate hydrolysis of methylumbelliferyl β-galactoside by β-glucosylceramidase and of galactocerebrocide by β-galactosylceramidase. For more details see Molecular Playground/Saposin C. Saposin B facilitates lipid binding to CD1d. Saposin D stimulates acid ceramidase activity. Disease Mutations in saposin B are autosomal recessive trait resulting in clinical metachromatic leukodystrophy. Mutations in saposin D cause urinary system defects.

3D Structures of Saposin

Updated on 21-January-2020

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• Saposin A residues 60-143
  • Lipid metabolism, Molecular Playground/Saposin C – hSapA – human
    
  • 4ddj – hSapA + LDAO
    
  • 5nxb – mSapA + galactocerebrosidase – mouse
    
• Saposin A residues 1-81
  • 6d80 – hSapA + mitochondrial calcium uniporter
    
• Saposin B
  • 1n69 – hSapB + lipid
    
  • 4v2o – hSapB + chloroquine
    
• Saposin C
  • 1m12, 1sn6 – hSapC – NMR
    
  • 2gtg, 2qyp, 2z9a – hSapC residues 311-391
• Saposin D
  • 3bqp, 3bqq, 2r1q, 2rb3 - hSapD residues 405-484
    
  • 5u85 - mSapD residues 438-519
    

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Michal Harel, Alexander Berchansky