Siglecs are immunoglobulin superfamily member lectins that selectively recognize different
types and linkages of sialic acids, which are major components of cell surface and secreted
glycoconjugates. We report here a human Siglec-like molecule (Siglec-L1) that lacks a
conserved arginine residue known to be essential for optimal sialic acid recognition by
previously known Siglecs. Loss of the arginine from an ancestral molecule was caused by a
single nucleotide substitution that occurred after the common ancestor of humans with the …