C-type lectin C-type lectin A C-type lectin (CLEC) is a type of carbohydrate-binding protein domain known as a lectin. The C-type designation is from their requirement for calcium for binding. Proteins that contain C-type lectin domains have a diverse range of functions including cell-cell adhesion, immune response to pathogens and apoptosis. Drickamer "et al." classified C-type lectins into 7 subgroups (I to VII) based on the order of the various protein domains in each protein. This classification was subsequently updated in 2002, leading to seven additional groups (VIII to XIV). Most recently, three further subgroups were added (XV to XVII). CLECs include:
Lectin MBL, the mannose-binding lectin, help mediate the first-line defense against invading microorganisms. Other lectins within the immune system are thought to play a role in self-nonself discrimination and they likely modulate inflammatory and autoreactive processes. Intelectins (X-type lectins) were shown to bind microbial glycans and may function in the innate immune system as well. Lectins may be involved in pattern recognition and pathogen elimination in the innate immunity of vertebrates including fishes. The function of lectins in plants (legume lectin) is still uncertain. Once thought to be necessary for rhizobia binding, this proposed function was ruled out through lectin-knockout transgene