Glycosylation-dependent cell adhesion molecule-1 (GLYCAM1) is a proteoglycan ligand expressed on cells of the high endothelial venules in lymphoid tissues. It is the ligand for the receptor L-selectin allowing for naive lymphocytes to exit the bloodstream into lymphoid tissues.[1][2]GLYCAM1 binds to L-selectin by presenting one or more O-linked carbohydrates to the lectin domain of the leukocyte cell surface selectin.[citation needed]Data suggests that GLYCAM1 is a hormone-regulated milk protein that is part of the milk mucin complex.[3]
GlyCAM-1 is expressed exclusively on high endothelial venules. It is unclear how GlyCAM-1 is attached to the membrane as it lacks a transmembrane region.[1]