Phosphorylation and ubiquitination of degron proximal residues are essential for class II transactivator (CIITA) transactivation and major histocompatibility class II expression.

Major histocompatibility (MHC) class II molecules are cell surface glycoproteins that present extracellular antigens to CD4(+) T cells and are essential for initiation of the adaptive immune response. MHC class II expression requires recruitment of a master regulator, the class II transactivator (CIITA), to the MHC class II promoter. Post-translational modifications to CIITA play important roles in modulating CIITA mediated transcription of various genes in different cell types.

Association of the 19S proteasomal ATPases with the ATPase-binding domain of CIITA is essential for CIITA stability and MHC class II expression.

Major histocompatibility class II (MHC class II) molecules are glycoproteins that present extracellular antigens to CD4(+) T cells and are essential for initiation of adaptive immune responses. MHC class II expression requires recruitment of a master regulator, the class II transactivator (CIITA), to the MHC class II promoter. Others and we have earlier linked CIITA to the ubiquitin-proteasome system by showing that mono-ubiquitination of CIITA increases its transactivity, whereas poly-ubiquitination of CIITA leads to its degradation.