An in vivo membrane density perturbation strategy for identification of liver sinusoidal surface proteome accessible from the vasculature.

Liver sinusoidal endothelial cells (LSEC), the predominant nonparenchyma cells in liver, play critical roles in many important physiological and pathological processes by virtue of their unique location at the blood-tissue interface. To uncover the protein composition of LSEC plasma membrane (PM) comprehensively and give implications for the tissue microenvironment heterogeneity, we have developed an in vivo modified membrane density perturbation method for purification of the PM fraction. The proteins were separated and identified by SDS-PAGE combined with LC-MS/MS (GeLC-MS/MS). A total of 837 nonredundant proteins were identified, including a number of proteins previously reported to be localized to the PM of LSEC, as well as others not described. A diversity of membrane proteins involved in signaling, traffic, transporting and adhesion functions were identified. Our results demonstrated that the in vivo membrane density perturbation was an effective strategy to purify LSEC PM.