2YG2: Structure of Apolioprotein M in Complex With Sphingosine 1-phosphate

Protection of the endothelium is provided by circulating sphingosine-1-phosphate (S1P), which maintains vascular integrity. We show that HDL-associated S1P is bound specifically to both human and murine apolipoprotein M (apoM). Thus, isolated human ApoM(+) HDL contained S1P, whereas ApoM(-) HDL did not. Moreover, HDL in Apom(-/-) mice contains no S1P, whereas HDL in transgenic mice overexpressing human apoM has an increased S1P content. The 1.7-A structure of the S1P-human apoM complex reveals that S1P interacts specifically with an amphiphilic pocket in the lipocalin fold of apoM. Human ApoM(+) HDL induced S1P(1) receptor internalization, downstream MAPK and Akt activation, endothelial cell migration, and formation of endothelial adherens junctions, whereas apoM(-) HDL did not. Importantly, lack of S1P in the HDL fraction of Apom(-/-) mice decreased basal endothelial barrier function in lung tissue. Our results demonstrate that apoM, by delivering S1P to the S1P(1) receptor on endothelial cells, is a vasculoprotective constituent of HDL.
PDB ID: 2YG2Download
MMDB ID: 90914
PDB Deposition Date: 2011/4/11
Updated in MMDB: 2011/10
Experimental Method:
x-ray diffraction
Resolution: 1.7  Å
Source Organism:
Similar Structures:
Biological Unit for 2YG2: monomeric; determined by author and by software (PISA)
Molecular Components in 2YG2
Label Count Molecule
Protein (1 molecule)
Apolipoprotein M(Gene symbol: APOM)
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB