4UEX

Structure of human Saposin A at lysosomal pH


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.210 
  • R-Value Work: 0.185 

wwPDB Validation 3D Report Full Report


This is version 1.0 of the entry. See complete history

Literature

Structure of Human Saposin a at Lysosomal Ph.

Hill, C.H.Read, R.J.Deane, J.E.

(2015) Acta Crystallogr.,Sect.D 71: 895

  • DOI: 10.1107/S2053230X15008584

  • PubMed Abstract: 
  • The saposins are essential cofactors for the normal lysosomal degradation of complex glycosphingolipids by acid hydrolase enzymes; defects in either saposin or hydrolase function lead to severe metabolic diseases. Saposin A (SapA) activates the enzym ...

    The saposins are essential cofactors for the normal lysosomal degradation of complex glycosphingolipids by acid hydrolase enzymes; defects in either saposin or hydrolase function lead to severe metabolic diseases. Saposin A (SapA) activates the enzyme β-galactocerebrosidase (GALC), which catalyzes the breakdown of β-D-galactocerebroside, the principal lipid component of myelin. SapA is known to bind lipids and detergents in a pH-dependent manner; this is accompanied by a striking transition from a `closed' to an `open' conformation. However, previous structures were determined at non-lysosomal pH. This work describes a 1.8 Å resolution X-ray crystal structure determined at the physiologically relevant lysosomal pH 4.8. In the absence of lipid or detergent at pH 4.8, SapA is observeed to adopt a conformation closely resembling the previously determined `closed' conformation, showing that pH alone is not sufficient for the transition to the `open' conformation. Structural alignments reveal small conformational changes, highlighting regions of flexibility.


    Organizational Affiliation

    Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, England.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
PROSAPOSIN
A, B
85Homo sapiensMutation(s): 0 
Gene Names: PSAP (GLBA, SAP1)
Find proteins for P07602 (Homo sapiens)
Go to Gene View: PSAP
Go to UniProtKB:  P07602
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.210 
  • R-Value Work: 0.185 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 34.170α = 90.00
b = 58.690β = 93.10
c = 35.160γ = 90.00
Software Package:
Software NamePurpose
XDSdata reduction
PHENIXrefinement
Aimlessdata scaling
PHASERphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2015-07-15
    Type: Initial release