1LN1: Crystal Structure Of Human Phosphatidylcholine Transfer Protein In Complex With Dilinoleoylphosphatidylcholine

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.
PDB ID: 1LN1Download
MMDB ID: 19966
PDB Deposition Date: 2002/5/2
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 2.4  Å
Source Organism:
Similar Structures:
Biological Unit for 1LN1: monomeric; determined by author
Molecular Components in 1LN1
Label Count Molecule
Protein (1 molecule)
Phosphatidylcholine Transfer Protein(Gene symbol: PCTP)
Molecule annotation
Chemical (1 molecule)
* Click molecule labels to explore molecular sequence information.

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