Background：

Lysosome associated membrane protein (LAMP1)， also known as lgp120 or lgpA， is a type 1 integral membrane protein that is transported from trans Golgi networks to endosomes and then lysosomes. Upon cell activation， LAMP1 transfer to the plasma membrane is dependent on a carboxyl terminal tyrosine based motif (YXXI). Perturbation in the spacing between the tyrosine based motif relative to the membrane abolishes lysosome localization of LAMP1. This mutant protein then cycles between the plasma membrane and the endosome. Cell surface LAMP1 and LAMP2 have been shown to promote adhesion of human peripheral blood mononuclear cells (PBMC) to vascular endothelium， therefore they are possibly involved in the adhesion of PBMCs to the site of inflammation.