Faculty Collaboration Database

Identification of lysosome-associated membrane protein-2 as an activation-dependent platelet surface glycoprotein. Blood 1992 Sep 15;80(6):1470-5

Date

09/15/1992

Pubmed ID

1520873

Scopus ID

2-s2.0-0026778775 (requires institutional sign-in at Scopus site)   84 Citations

Abstract

Platelets undergo biochemical and morphologic changes when stimulated that greatly alter their function and contribute to their role in thrombosis and hemostasis. We recently identified and cloned the cDNA for a platelet surface glycoprotein expressed on activated, not resting cells. We found that this protein, lysome-associated membrane protein-1 (LAMP-1), is an integral membrane protein of the lysosome that translocated to the surface membrane when platelets were stimulated by a strong agonist. We now show with immunofluorescence flow cytometry that LAMP-2, a lysosomal membrane protein that shares approximately 30% homology with LAMP-1, is also expressed preferentially on the surface of activated platelets. Equilibrium binding studies with 125I-anti-LAMP-2 IgG showed approximately 1,100 binding sites per thrombin-stimulated platelet and less than 50 per resting platelet. Sucrose gradient ultracentrifugation fractionation of resting platelet sonicates showed that LAMP-2 colocalized with LAMP-1 and with lysosomal enzymes, and not with thrombospondin or serotonin, which are markers of the two other platelet granule compartments, alpha-granules and dense granules. LAMP-2 surface expression was minimal in response to platelet stimulation by weak agonists such as epinephrine and ADP. These data show that LAMP-2, like LAMP-1, translocates from the lysosomal membrane compartment to the surface membrane when platelets are activated. Regulated surface expression of these heavily glycosylated proteins may play a role in the adhesive, prothrombotic phenotype of these cells.

Author List

Silverstein RL, Febbraio M

Author

Roy L. Silverstein MD Professor in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Antibodies, Monoclonal
Antigens, CD
Blood Platelets
Humans
Membrane Glycoproteins
Molecular Structure
Platelet Activation
Protein Binding