Soluble Monomeric P-selectin Containing only the Lectin and EGF Domains Binds to PSGL-1 on Leukocytes
Abstract
Under shear stress, leukocytes use P-selectin glycoprotein ligand-1 (PSGL-1) to tether to and roll on P-selectin expressed on activated platelets or endothelial cells. P-selectin has an NH2-terminal lectin domain, an epidermal growth factor (EGF)-like motif, nine consensus repeats (CRs), a transmembrane domain, and a cytoplasmic tail. To determine whether the CRs are required for P-selectin to bind PSGL-1, we expressed a soluble protein (Lec-EGF) that contained only the lectin and EGF domains, plus a short C-terminal epitope tag. Electron microscopy and hydrodynamic analysis confirmed that Lec-EGF was monomeric, as previously shown for soluble P-selectin (sPS) that contained the lectin and EGF domains plus all nine CRs. Fluid-phase Lec-EGF or sPS inhibited binding of oligomeric125I-labeled membrane-derived P-selectin (mPS) to PSGL-1 on neutrophils and binding of 125I-PSGL-1 to immobilized mPS. The IC50 for inhibiting binding of mPS to neutrophils was fivefold greater for Lec-EGF than for sPS, whereas the IC50 for inhibiting binding of mPS to purified PSGL-1 was indistinguishable for Lec-EGF and sPS. Under static or shear conditions, neutrophils used PSGL-1 to tether to or roll on Lec-EGF that was captured by an immobilized monoclonal antibody to the C-terminal epitope. These data show that P-selectin requires only the lectin and EGF domains to bind to PSGL-1.
Department
Molecular, Cellular and Biomedical Sciences
Publication Date
9-15-1997
Journal Title
Blood
Publisher
American Society of Hematology
Digital Object Identifier (DOI)
Document Type
Article
Recommended Citation
Mehta, P., Patel, K.D., Laue, T.M., Erickson, H.P. and McEver, R.P. (1997) "Soluble Monomeric P-selectin Containing only the Lectin and EGF Domains Binds to PSGL-1 on Leukocytes." Blood, 90, 2381-2389.