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Saposin

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{{STRUCTURE_2dob| PDB=2dob | SIZE=400| SCENE= |right|CAPTION=Human saposin A complex with Ca+2 ion, [[2dob]] }}
{{STRUCTURE_2dob| PDB=2dob | SIZE=400| SCENE= |right|CAPTION=Human saposin A complex with Ca+2 ion, [[2dob]] }}
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== Function ==
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'''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 and 2 SapA domains which are cleaved off<ref>PMID:2001789</ref>.
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'''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 and 2 SapA domains which are cleaved off. For more details see [[Molecular Playground/Saposin C]].
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*'''Saposin A and C''' stimulate hydrolysis of methylumbelliferyl β-galactoside by β-glucosylceramidase and of galactocerebrocide by β-galactosylceramidase<ref>PMID:2717620</ref>. For more details see [[Molecular Playground/Saposin C]].<br />
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*'''Saposin B''' facilitates lipid binding to CD1d<ref>PMID:17372201</ref>.<br />
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*'''Saposin D''' stimulates acid ceramidase activity<ref>PMID:8203897</ref>.<br />
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== Disease ==
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Mutations in saposin B are autosomal recessive trait resulting in clinical metachromatic leukodystrophy<ref>PMID:17616409</ref>. Mutations in saposin D cause urinary system defects<ref>PMID:15345707</ref>.
== 3D Structures of Saposin ==
== 3D Structures of Saposin ==
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**[[3bqp]], [[3bqq]], [[2r1q]], [[2rb3]] - hSapD residues 405-484<br />
**[[3bqp]], [[3bqq]], [[2r1q]], [[2rb3]] - hSapD residues 405-484<br />
}}
}}
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== References ==
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<references/>
[[Category:Topic Page]]
[[Category:Topic Page]]

Revision as of 09:20, 23 August 2016

Template:STRUCTURE 2dob

Contents

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 and 2 SapA domains which are cleaved off[1].

  • Saposin A and C stimulate hydrolysis of methylumbelliferyl β-galactoside by β-glucosylceramidase and of galactocerebrocide by β-galactosylceramidase[2]. For more details see Molecular Playground/Saposin C.
  • Saposin B facilitates lipid binding to CD1d[3].
  • Saposin D stimulates acid ceramidase activity[4].

Disease

Mutations in saposin B are autosomal recessive trait resulting in clinical metachromatic leukodystrophy[5]. Mutations in saposin D cause urinary system defects[6].

3D Structures of Saposin

Updated on 23-August-2016

References

  1. ↑ O'Brien JS, Kishimoto Y. Saposin proteins: structure, function, and role in human lysosomal storage disorders. FASEB J. 1991 Mar 1;5(3):301-8. PMID:2001789
  2. ↑ Morimoto S, Martin BM, Yamamoto Y, Kretz KA, O'Brien JS, Kishimoto Y. Saposin A: second cerebrosidase activator protein. Proc Natl Acad Sci U S A. 1989 May;86(9):3389-93. PMID:2717620
  3. ↑ Yuan W, Qi X, Tsang P, Kang SJ, Illarionov PA, Besra GS, Gumperz J, Cresswell P. Saposin B is the dominant saposin that facilitates lipid binding to human CD1d molecules. Proc Natl Acad Sci U S A. 2007 Mar 27;104(13):5551-6. Epub 2007 Mar 19. PMID:17372201 doi:http://dx.doi.org/10.1073/pnas.0700617104
  4. ↑ Azuma N, O'Brien JS, Moser HW, Kishimoto Y. Stimulation of acid ceramidase activity by saposin D. Arch Biochem Biophys. 1994 Jun;311(2):354-7. PMID:8203897
  5. ↑ Deconinck N, Messaaoui A, Ziereisen F, Kadhim H, Sznajer Y, Pelc K, Nassogne MC, Vanier MT, Dan B. Metachromatic leukodystrophy without arylsulfatase A deficiency: a new case of saposin-B deficiency. Eur J Paediatr Neurol. 2008 Jan;12(1):46-50. Epub 2007 Jul 5. PMID:17616409 doi:http://dx.doi.org/10.1016/j.ejpn.2007.05.004
  6. ↑ Matsuda J, Kido M, Tadano-Aritomi K, Ishizuka I, Tominaga K, Toida K, Takeda E, Suzuki K, Kuroda Y. Mutation in saposin D domain of sphingolipid activator protein gene causes urinary system defects and cerebellar Purkinje cell degeneration with accumulation of hydroxy fatty acid-containing ceramide in mouse. Hum Mol Genet. 2004 Nov 1;13(21):2709-23. Epub 2004 Sep 2. PMID:15345707 doi:http://dx.doi.org/10.1093/hmg/ddh281

Proteopedia Page Contributors and Editors (what is this?)

Michal Harel, Alexander Berchansky

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