Rat PITP-Beta Complexed to Phosphatidylcholine

Experimental Data Snapshot

  • Resolution: 2.18 Å
  • R-Value Free: 0.257 
  • R-Value Work: 0.210 
  • R-Value Observed: 0.210 

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Structure of PITPbeta in Complex with Phosphatidylcholine: Comparison of Structure and Lipid Transfer to Other PITP Isoforms.

Vordtriede, P.B.Doan, C.N.Tremblay, J.M.Helmkamp, G.M.Yoder, M.D.

(2005) Biochemistry 44: 14760-14771

  • DOI: https://doi.org/10.1021/bi051191r
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Phosphatidylinositol transfer protein (PITP) is a ubiquitous eukaryotic protein that preferentially binds either phosphatidylinositol or phosphatidylcholine and catalyzes the exchange of these lipids between membranes. Mammalian cytosolic PITPs include the ubiquitously expressed PITPalpha and PITPbeta isoforms (269-270 residues). The crystal structure of rat PITPbeta complexed to dioleoylphosphatidylcholine was determined to 2.18 A resolution with molecular replacement using rat PITPalpha (77% sequence identify) as the phasing model. A structure comparison of the alpha and beta isoforms reveals minimal differences in protein conformation, differences in acyl conformation in the two isoforms, and remarkable conservation of solvent structure around the bound lipid. A comparison of transfer activity by human and rat PITPs, using small unilamellar vesicles with carefully controlled phospholipid composition, indicates that the beta isoforms have minimal differences in transfer preference between PtdIns and PtdCho when donor vesicles contain predominantly PtdCho. When PtdCho and PtdIns are present in equivalent concentrations in donor vesicles, PtdIns transfer occurs at approximately 3-fold the rate of PtdCho. The rat PITPbeta isoform clearly has the most diminished transfer rate of the four proteins studied. With the two rat isoforms, site-directed mutations of two locations within the lipid binding cavity that possess differing biochemical properties were characterized: I84alpha/F83beta and F225alpha/L224beta. The 225/224 locus is more critical in determining substrate specificity. Following the mutation of this locus to the other amino acid, the PtdCho transfer specific activity became PITPalpha (F225L) approximately PITPbeta and PITPbeta (L224F) approximately PITPalpha. The 225alpha/224beta locus plays a modest role in the specificity of both isoforms toward CerPCho.

  • Organizational Affiliation

    Division of Cell Biology and Biophysics, University of Missouri-Kansas City, Kansas City, Missouri 64110-2499, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Phosphatidylinositol transfer protein beta isoform270Rattus norvegicusMutation(s): 0 
Gene Names: Pitpnb
Membrane Entity: Yes 
Find proteins for P53812 (Rattus norvegicus)
Explore P53812 
Go to UniProtKB:  P53812
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP53812
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on PCW

Download Ideal Coordinates CCD File 
C44 H85 N O8 P
Experimental Data & Validation

Experimental Data

  • Resolution: 2.18 Å
  • R-Value Free: 0.257 
  • R-Value Work: 0.210 
  • R-Value Observed: 0.210 
  • Space Group: P 43 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 65.945α = 90
b = 65.948β = 90
c = 133.513γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
SCALEPACKdata scaling
HKL-2000data reduction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2005-11-29
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2023-08-23
    Changes: Data collection, Database references, Derived calculations, Refinement description