Crystal structure of MHC class II-associated p41 Ii fragment bound to cathepsin L reveals the structural basis for differentiation between cathepsins L and S

A role for cathepsin L and cathepsin S in peptide generation for MHC class II presentation.

The enzymes that degrade proteins to peptides for presentation on MHC class II molecules are poorly understood. The cysteinal lysosomal proteases, cathepsin L (CL) and cathepsin S (CS), have been shown to process invariant chain, thereby facilitating MHC class II maturation. However, their role in Ag processing is not established. To examine this issue, we generated embryonic fibroblast lines t...

Major histocompatibility complex class II-associated p41 invariant chain fragment is a strong inhibitor of lysosomal cathepsin L

The invariant chain (Ii) is associated with major histocompatibility complex class II molecules during early stages of their intracellular transport. In an acidic endosomal/lysosomal compartment, it is proteolytically cleaved and removed from class II heterodimers. Participation of aspartic and cysteine proteases has been observed in in vitro degradation of Ii, but the specific enzymes responsi...

Human cathepsin S, but not cathepsin L, degrades efficiently MHC class II-associated invariant chain in nonprofessional APCs.

MHC class II-restricted antigen presentation plays a central role in the immune response against exogenous antigens. The association of invariant (Ii) chain with MHC class II dimers is required for proper antigen presentation to CD4+ T cells by antigen-presenting cells. MHC class II complexes first traffic through the endocytic pathway to allow Ii chain degradation and antigenic peptide loading...

Shark class II invariant chain reveals ancient conserved relationships with cathepsins and MHC class II.

The invariant chain (Ii) is the critical third chain required for the MHC class II heterodimer to be properly guided through the cell, loaded with peptide, and expressed on the surface of antigen presenting cells. Here, we report the isolation of the nurse shark Ii gene, and the comparative analysis of Ii splice variants, expression, genomic organization, predicted structure, and function throu...

Not second class: the first class II MHC crystal structure.