Advanced Antigen Processing and Presentation

Endogenous Antigens

Antigens presented by MHC I molecules that are synthesised within the cell itself.

Exogenous Antigens

Antigens presented by MHC II molecules that are taken into the cell from the extracellular environment.

Polyubiquitination

A process that tags proteins with ubiquitin chains for destruction by the proteasome.

E1 (Ubiquitin-activating enzyme)

The enzyme that activates ubiquitin to begin the polyubiquitination process.

E2 (Ubiquitin-conjugating enzyme)

A carrier protein that receives activated ubiquitin from E1.

E3 (Ubiquitin ligase)

An enzyme that recognises specific target proteins and catalyses the transfer of ubiquitin from E2 to the target.

DRiP Hypothesis

The theory that protein synthesis is inefficient and generates many Defective Ribosomal Products (DRiPs) like misfolded or incomplete polypeptides, which are tagged for degradation.

Immunoproteasome

A specialized proteasome where constitutive subunits $\beta 1$, $\beta 2$, and $\beta 5$ are replaced by $\beta 1\text{i}$ (LMP2), $\beta 2\text{i}$ (MECL-1), and $\beta 5\text{i}$ (LMP7) to generate antigenic peptides.

PA