C-Type Lectins

C-type lectins (CTLs) are Ca-dependent glycan-binding proteins (GBPs) that share primary and secondary structural homology in their carbohydrate-recognition domains (CRDs). The CRD of CTLs is more generally defined as the CTL domain (CTLD), because not all proteins with this domain bind either glycans or Ca. CTLs include collectins, selectins, endocytic receptors, and proteoglycans, some of which are secreted and others are transmembrane proteins. They often oligomerize, which increases their avidity for multivalent ligands and enhance recognition of pattern recognition receptor (PRRs). CTLs differ significantly in the types of ligands that they recognize with high affinity (e.g., glycans, proteins, lipids, and inorganic compounds). These proteins that recognize pathogens or self-expressed ligands function as adhesion, phagocytic, and signaling receptors in many pathways, including homeostasis and innate and adaptive immunity, and are crucial in inflammatory responses, leukocyte and platelet trafficking, and tissue remodeling.