TAPBP

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Description

The TAPBP (TAP binding protein) is a protein-coding gene located on chromosome 6.

TAP-associated glycoprotein, also known as tapasin or TAPBP, is a protein that in humans is encoded by the TAPBP gene. The TAPBP gene encodes a transmembrane glycoprotein that mediates interaction between newly assembled major histocompatibility complex (MHC) class I molecules and the transporter associated with antigen processing (TAP), which is required for the transport of antigenic peptides across the endoplasmic reticulum membrane. This interaction facilitates optimal peptide loading on the MHC class I molecule. Up to four complexes of MHC class I and tapasin may be bound to a single TAP molecule. Tapasin contains a C-terminal double-lysine motif (KKKAE) known to maintain membrane proteins in the endoplasmic reticulum. In humans, the tapasin gene lies within the major histocompatibility complex on chromosome 6. Alternative splicing results in three transcript variants encoding different isoforms. Tapasin is a MHC class I antigen-processing molecule present in the lumen of the endoplasmic reticulum. It plays an important role in the maturation of MHC class I molecules in the ER lumen. Tapasin is one component of the peptide-loading complex, and can be found associated with MHC class I molecules after the MHC class I heavy chain has associated with Beta2 microglobulin.

Involved in the association of MHC class I with transporter associated with antigen processing (TAP) and in the assembly of MHC class I with peptide (peptide loading).

TAPBP is also known as MHC1D3, NGS17, TAPA, TPN, TPSN.

Associated Diseases

• MHC class I deficiency
• severe combined immunodeficiency due to CTPS1 deficiency
• immunodeficiency 18
• severe combined immunodeficiency due to CARD11 deficiency
• reticular dysgenesis
• Wiskott-Aldrich syndrome
• combined immunodeficiency with skin granulomas
• immunodeficiency 105
• common variable immunodeficiency
• severe combined immunodeficiency due to LAT deficiency
• immunodeficiency 99 with hypogammaglobulinemia and autoimmune cytopenias