PDBsum entry 1ln1

Lipid binding protein

PDB id: 1ln1

Contents

Protein chain

203 a.a. *

Ligands

DLP

Waters ×34

* Residue conservation analysis

PDB id:

1ln1

Name:

Lipid binding protein

Title:

Crystal structure of human phosphatidylcholine transfer protein in complex with dilinoleoylphosphatidylcholine

Structure:

Phosphatidylcholine transfer protein. Chain: a. Synonym: pc-tp. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Expressed in: escherichia coli. Expression_system_taxid: 562

Biol. unit:

Octamer (from PQS)

Resolution:

2.40Å R-factor: 0.234 R-free: 0.296

Authors:

S.L.Roderick,W.W.Chan,D.S.Agate,L.R.Olsen,M.W.Vetting, K.R.Rajashankar,D.E.Cohen

Key ref:

S.L.Roderick et al. (2002). Structure of human phosphatidylcholine transfer protein in complex with its ligand. Nat Struct Biol, 9, 507-511. PubMed id: 12055623 DOI: 10.1038/nsb812

Date:

02-May-02 Release date: 26-Jun-02

Protein chain

Q9UKL6  (PPCT_HUMAN) -  Phosphatidylcholine transfer protein from Homo sapiens

Seq: 214 a.a.

Struc: 203 a.a.

DOI no: 10.1038/nsb812

Nat Struct Biol 9:507-511 (2002)

PubMed id: 12055623

Structure of human phosphatidylcholine transfer protein in complex with its ligand.

S.L.Roderick, W.W.Chan, D.S.Agate, L.R.Olsen, M.W.Vetting, K.R.Rajashankar, D.E.Cohen.

ABSTRACT

Phosphatidylcholines (PtdChos) comprise the most common phospholipid class in eukaryotic cells. In mammalian cells, these insoluble molecules are transferred between membranes by a highly specific phosphatidylcholine transfer protein (PC-TP) belonging to the steroidogenic acute regulatory protein related transfer (START) domain superfamily of hydrophobic ligand-binding proteins. The crystal structures of human PC-TP in complex with dilinoleoyl-PtdCho or palmitoyl-linoleoyl-PtdCho reveal that a single well-ordered PtdCho molecule occupies a centrally located tunnel. The positively charged choline headgroup of the lipid engages in cation-pi interactions within a cage formed by the faces of three aromatic residues. These binding determinants and those for the phosphoryl group may be exposed to the lipid headgroup at the membrane-water interface by a conformational change involving the amphipathic C-terminal helix and an Omega-loop. The structures presented here provide a basis for rationalizing the specificity of PC-TP for PtdCho and may identify common features used by START proteins to bind their hydrophobic ligands.

Selected figure(s)

Figure 2.
Figure 2. Structural comparison of START domains. Stereo view superposition of the C traces of PC-TP (blue) and MLN64 (gray) based on 126 paired C positions. The most similar regions are the -strands of the central -sheet that form the floor of the lipid binding tunnel, whereas the most significant differences include the positioning of loop 1 and the C-terminal helix.

Figure 3.
Figure 3. The PtdCho-binding pocket. a, Views of the solvent accessible volume of the binding pocket, separated by a 90° rotation. b, Stereo view of the interactions of PC-TP with the glycerol-3-phosphorylcholine moiety of PLPC (yellow). The structure of DLPC from the PC-TP−DLPC complex is superimposed (gray). c, Stereo view of the interactions of the phosphorylcholine quaternary amine with PC-TP (yellow) and the trimethyllysine residue of the histone H3 tail with HP1 (ref. 24) (gray). The residues of the three-walled aromatic cage of PC-TP are labeled.

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nat Struct Biol (2002, 9, 507-511) copyright 2002.

Figures were selected by an automated process.