Human Leukocyte Antigen (HLA) part 51

In most cases to date, this low expression is due to a homozygous in activating mutation in one of the two subunits of the transporter associated with antigen processing, critically involved in the peptide loading of HLA class I molecules.  Transporter associated with antigen processing deficiency has been molecularly characterized by a point mutation leading to a premature  stop codon,  with or without frame-shift, and thus to a truncated and non-functional protein. The asymptomatic transporter associated with antigen processing deficient siblings have a mutation in the gene region encoding the ATP-binding cassette that destroys the activity of transporter associated with antigen processing 2, although interactions with transporter associated with antigen I and tapasin should be preserved.