"MHC class II proteins have an overall similar structure to MHC class I proteins, although their subunit structure is distinct. MHC class II proteins are composed of two subunits that contribute to the structure of the head domain containing the antigen-binding groove. As a rule, MHC class II proteins bind longer peptides than MHC class I proteins. As seen in this comparison, the different shape of the antigen-binding groove allows the ends of the peptide to stick out. MHC class II proteins display peptides on the surfaces of specialized antigen-presenting cells and activate a different class of immune cells, called helper T cells."
Essential Cell Biology, Second Edition
by Alberts, Bray, Hopkin, Johnson, Lewis, Raff, Roberts, Walter
copyright 2004 by Garland Science Publishing
