CLIP (protein)

CLIP or Class II-associated invariant chain peptide is the part of the invariant chain (Ii) that binds to the peptide binding groove of MHC class II and remains there until the MHC receptor is fully assembled.

CLIP is one of the most prevalent self peptides found in the thymic cortex[broken anchor] of most antigen-presenting cells.

In a late endosome/early lysosome, cathepsin S cleaves the invariant chain, leaving CLIP bound to the MHC II complex.

Antigenic peptides have a high affinity for the MHC II groove, and are readily exchanged for CLIP.

Both HLA-DM and HLA-DO interact with each other to act as chaperone proteins and prevent the denaturing of MHC II.

MHC II bound to invariant chain. Cathepsin S cleaves Ii, leaving CLIP bound. CLIP is readily exchanged for antigenic peptides, using HLA-DM as a chaperone protein.