GMP-140, a platelet alpha-granule membrane protein, is also synthesized by vascular endothelial cells and is localized in Weibel-Palade bodies.
We used an immunoperoxidase procedure to examine the tissue distribution of the platelet alpha-granule membrane protein, GMP-140. In addition to its presence in megakaryocytes and platelets, GMP-140 antigen was found in vascular endothelial cells of diverse human organs, but it was not detected in other types of secretory cells. [35S]Cysteine-labeled human umbilical vein endothelial cells synthesized a GMP-140 molecule containing complex N-linked oligosaccharides similar to those previously demonstrated in platelets and the megakaryocytic HEL cell line. Using an immunogold procedure on frozen thin sections of endothelial cells, we found GMP-140 antigen to be localized to membranes of electron-dense storage granules. In double-label experiments there was colocalization of GMP-140 with vWf, indicating that these granules are Weibel-Palade bodies. When endothelial cells were stimulated with histamine, GMP-140 rapidly redistributed to the plasma membrane. Immunoassays of cell lysates indicated that, relative to total cell protein, less GMP-140 is present in human umbilical vein endothelial cells than in platelets. The restricted expression of GMP-140 in secretory granules of platelets and endothelium suggests that it has a specific function in the vascular system rather than a general role related to inducible secretion.
McEver
R P
RP
St. Francis Medical Research Institute, University of Oklahoma Health Science Center, Oklahoma City 73104.
Beckstead
J H
JH
Moore
K L
KL
Marshall-Carlson
L
L
Bainton
D F
DF
D002478:Cells, Cultured; D003594:Cytoplasmic Granules / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000648:ultrastructure; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007150:Immunohistochemistry; D019007:P-Selectin; D010980:Platelet Membrane Glycoproteins / Q000096:biosynthesis* / Q000378:metabolism; D014018:Tissue Distribution
D019007:P-Selectin; D010980:Platelet Membrane Glycoproteins