Localization of protein disulfide isomerase to the external surface of the platelet plasma membrane.
Protein disulfide isomerase (PDI) is an enzyme that catalyzes the formation as well as the isomerization of disulfide bonds. In this study, antibodies against PDI were used to show PDI antigen on the platelet surface by indirect immunofluorescence microscopy and by flow cytometry. The platelets were not activated, as evidenced by the absence of staining by an antibody against P-selectin. Permeabilized platelets showed little cytosolic PDI by indirect immunofluorescence microscopy, suggesting that the majority of platelet PDI is localized to the platelet surface. PDI activity against "scrambled" RNase was shown with intact platelets. The activity was inhibited by inhibitors of PDI and by an antibody against PDI. Other blood cells showed little PDI. Platelet surface PDI may play a role in the various physiological and pathophysiologic processes in which platelets are involved.
Essex
D W
DW
Department of Medicine, State University of New York, Health Science Center at Brooklyn 11203, USA.
Chen
K
K
Swiatkowska
M
M
D000818:Animals; D001773:Blood Cells / Q000201:enzymology; D001792:Blood Platelets / Q000201:enzymology* / Q000648:ultrastructure; D001853:Bone Marrow / Q000201:enzymology / Q000473:pathology; D002462:Cell Membrane / Q000201:enzymology*; D002463:Cell Membrane Permeability; D005434:Flow Cytometry; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D007535:Isomerases / Q000032:analysis* / Q000276:immunology; D008533:Megakaryocytes / Q000201:enzymology / Q000648:ultrastructure; D008565:Membrane Proteins / Q000032:analysis*; D008856:Microscopy, Fluorescence; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000473:pathology; D019704:Protein Disulfide-Isomerases; D011817:Rabbits
D007140:Immunoglobulin Fab Fragments; D008565:Membrane Proteins; D007535:Isomerases; D019704:Protein Disulfide-Isomerases