title: Molecular stiffness of selectins.
abstract: During inflammation, selectin-ligand interactions provide forces for circulating leukocytes to adhere to vascular surfaces, which stretch the interacting molecules, suggesting that mechanical properties may be pertinent to their biological function. From mechanical measurements with atomic force microscopy, we analyzed the molecular characteristics of selectins complexed with ligands and antibodies. Respective stiffness of L-, E-, and P-selectins (4.2, 1.4, and 0.85 piconewton/nm) correlated inversely with the number (2, 6, and 9) of consensus repeats in the selectin structures that acted as springs in series to dominate their compliance. After reconstitution into a lipid bilayer, purified membrane P-selectin remained a dimer, capable of forming dimeric bonds with P-selectin glycoprotein ligand (PSGL)-1, endoglycan-Ig, and a dimeric form of a glycosulfopeptide modeled after the N terminus of PSGL-1. By comparison, purified membrane L- and E-selectin formed only monomeric bonds under identical conditions. Ligands and antibodies were much less stretchable than selectins. The length of endoglycan-Ig was found to be 51 ± 12 nm. These results provide a comprehensive characterization of the molecular stiffness of selectins and illustrate how mechanical measurements can be utilized for molecular analysis, e.g. evaluating the multimericity of selectins and determining the molecular length of endoglycan.
authors.affiliation: Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
authors.forename: Krishna K
authors.initials: KK
authors.lastname: Sarangapani
authors.forename: Bryan T
authors.initials: BT
authors.lastname: Marshall
authors.forename: Rodger P
authors.initials: RP
authors.lastname: McEver
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhu
mesh_terms: D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D008051:Lipid Bilayers; D018625:Microscopy, Atomic Force; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D019087:Selectins / Q000737:chemistry* / Q000235:genetics
chemical_list: D008051:Lipid Bilayers; D011994:Recombinant Proteins; D019087:Selectins