A C-type lectin (CLEC) is a type of carbohydrate-binding protein known as a lectin.[1] 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.[2] [3]
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.[4] This classification was subsequently updated in 2002, leading to seven additional groups (VIII to XIV).[5] Most recently, three further subgroups were added (XV to XVII).[1]
| Group | Name | Associated domains | |
|---|---|---|---|
| I | Lecticans | EGF, Sushi, Ig and Link domains | |
| II | Asialoglycoprotein and DC receptors | None | |
| III | Collectins | None | |
| IV | Selectins | Sushi and EGF domains | |
| V | NK - cell receptors | None | |
| VI | Multi-CTLD endocytic receptors | FnII and Ricin domains | |
| VII | Reg group | None | |
| VIII | None | ||
| IX | None | ||
| X | WSC, REJ, PKD domains | ||
| XI | Attractin (ATRN) | PSI, EGF and CUB domains | |
| XII | Eosinophil major basic protein (EMBP) | None | |
| XIII | None | ||
| XIV | EGF domains [6] | ||
| XV | None | ||
| XVI | SEEC | SCP and EGF domains | |
| XVII | CBCP/Frem1/QBRICK | CSPG repeats and CalX-beta domains |
CLECs include:
The "NK Cell lectin-like receptors" are a very closely related group:
Additional proteins containing this domain include: