Schematics of the P-selectin constructs. mPS contains an NH₂-terminal lectin domain (lectin), followed by an EGF-like domain (EGF), nine consensus repeats (CR1-9) related to those in complement-regulatory proteins, a transmembrane domain (TM), and a cytoplasmic tail (cyto). sPS terminates with Ala₇₃₀ at the junction of CR9 with the transmembrane domain. Lec-EGF contains the lectin and EGF domains (residues 1-156), plus a C-terminal extension that includes a factor Xa cleavage site and the epitope for the MoAbs HPC4 and 1478. Native mPS was purified from human platelets. Recombinant sPS and Lec-EGF were purified from the conditioned medium of transfected 293 cells. Not shown is the NH₂-terminal signal peptide that is cleaved after synthesis of all three proteins.