R-Type Lectins

The R-type lectins are members of a superfamily of proteins that contain a carbohydrate-recognition domain (CRD) that is structurally similar to the one in ricin. Ricin is considered the first lectin to be discovered, and it is thus the prototypical lectin in this category. R-type lectins are present in plants, animals, and bacteria, and the lectin domain in some cases is associated with a separate subunit that is a potent toxin. The structure–function relationships of this group of proteins are discussed in this chapter.