C-type lectins

One of two classes of lectin produced by animal cells, the other being the S-type. The C-type lectins require disulphide-linked cysteines and Ca2+ ions in order to bind to a specific carbohydrate (cf. S-type lectins). The carbohydrate recognition domain of C-type lectins consists of about 130 amino acids which contains 18 invariant residues in a highly conserved pattern. These invariant residues include cysteines which probably form disulphide bonds. So far, all identified C-type lectins are extracellular proteins and include both integral membrane proteins, such as the asialoglycoprotein receptor, and soluble proteins.