Structural and functional characterization of monomeric soluble P-selectin and comparison with membrane P-selectin.

Published

Journal Article

P-selectin is an adhesion receptor for leukocytes on thrombin-activated platelets and endothelial cells. It contains a NH2-terminal carbohydrate-recognition domain, an epidermal growth factor motif, nine consensus repeats, a transmembrane domain, and a cytoplasmic tail. We expressed two soluble forms of P-selectin, one truncated after the ninth repeat (tPS) and the other lacking the transmembrane domain due to alternative RNA splicing (asPS). When visualized by electron microscopy, each was a monomeric rod-like structure with a globular domain at one end, whereas membrane P-selectin (mPS) from platelets formed rosettes with the globular domains facing outward. Sedimentation velocity and equilibrium studies confirmed that tPS and asPS were asymmetric monomers, whereas mPS was oligomeric. HL-60 cells adhered to immobilized tPS and asPS, although less efficiently than to mPS. 125I-Labeled tPS and asPS bound to approximately 25,000 sites/neutrophil and approximately 36,000 sites/HL-60 cell with an apparent Kd of 70 nM. Treatment of HL-60 cells with O-sialoglycoprotease eliminated the binding sites for asPS. We conclude that 1) P-selectin is a rigid, asymmetric protein; 2) monomeric soluble P-selectin binds to high affinity ligands with sialylated O-linked oligosaccharides on leukocytes; and 3) oligomerization of mPS enhances its avidity for leukocytes.

Full Text

Duke Authors

Cited Authors

  • Ushiyama, S; Laue, TM; Moore, KL; Erickson, HP; McEver, RP

Published Date

  • July 15, 1993

Published In

Volume / Issue

  • 268 / 20

Start / End Page

  • 15229 - 15237

PubMed ID

  • 7686912

Pubmed Central ID

  • 7686912

International Standard Serial Number (ISSN)

  • 0021-9258

Language

  • eng

Conference Location

  • United States