[3] The C-type designation is from their requirement for calcium for binding.

[4] Proteins that contain C-type lectin domains have a diverse range of functions including cell-cell adhesion, immune response to pathogens and apoptosis.

[7] This classification was subsequently updated in 2002, leading to seven additional groups (VIII to XIV).

[8] Most recently, three further subgroups were added (XV to XVII).

[3] CLECs include: The "NK Cell lectin-like receptors" are a very closely related group:[10] Additional proteins containing this domain include: