Putative adhesion molecule that mediates sialic-acid dependent binding to cells. The sialic acid recognition site may be masked by cis interactions with sialic acids on the same cell surface. Isoform Short is highly expressed in spleen, small intestine and adrenal gland; it is lower expressed in thyroid, placenta, brain, stomach, bone marrow, spinal cord and breast. Isoform Long is highly expressed in spleen, small intestine and bone marrow; it is lower expressed in thyroid, placenta, thymus, trachea, stomach, lung, adrenal gland, fetal brain and testis. Contains 1 copy of a cytoplasmic motif that is referred to as the immunoreceptor tyrosine-based inhibitor motif (ITIM). This motif is involved in modulation of cellular responses. The phosphorylated ITIM motif can bind the SH2 domain of several SH2-containing phosphatases. Belongs to the immunoglobulin superfamily. SIGLEC (sialic acid binding Ig-like lectin) family. Siglec-L1