The E-selectin-ligand ESL-1 is a variant of a receptor for fibroblast growth factor

E-SELECTIN is an inducible cell-adhesion molecule on endothelial cells, which mediates the binding of neutrophils and functions as a Ca²⁺-dependent lectin^1–3. We have recently identified a 150K glycoprotein as the major ligand for E-selectin on myeloid cells, using a recombinant antibody-like form of mouse E-selectin as an affinity probe^{4, 5}. Here we report the isolation of a mouse complementary DNA for this E-selectin ligand (ESL-1). The predicted amino-acid sequence of ESL-1 is 94% identical (over 1, 078 amino acids) to the recently identified chicken cysteine-rich fibroblast growth-factor receptor⁶, except for a unique 70-amino-acid amino-terminal domain of mature ESL-1. Fucosylation of ESL-1 is imperative for affinity isolation with E-selectin-IgG. A fucosylated, recombinant antibody-like form of ESL-1, but not of L-selectin, supports adhesion of E-selectin-transfected Chinese hamster ovary cells. Antibodies against ESL-1 block the binding of mouse myeloid cells to E-selectin. ESL-1, with a structure essentially identical to that of a receptor, thus functions as a cell adhesion ligand of E-selectin.