TAP1 Gene

TAP1 (TAP1 stands for "Transporter 1, ATP Binding Cassette Subfamily B Member") is a protein coding gene located on chromosome 6p21.32. Two transcript variants have been found for the TAP1 gene, coding for different isoforms.

The protein encoded by the TAP1 gene is a member of the MDR/TAP family (its members are involved in multidrug resistance). The ABC transporter TAP-1 protein is involved in antigen processing. It pumps degraded cytosolic peptides through the endoplasmic reticulum into the membrane-bound compartment, where class I molecules are located. Here, these are loaded with the antigen. To transport peptides against the concentration gradient, the chemical energy of ATP is used. Binding of the peptide antigen to the ATP-loaded TAP1-TAP2 results in a switch to a hydrolysis-ready "outward" conformation, ready to load the peptide onto the nascent MHCI molecules. Subsequently, ATP hydrolysis resets the transporter to the "inward-facing" state for a new cycle.

Diseases associated with TAP1 include.

• "Bare lymphocyte syndrome, type I" (de la Salle H et al. 1999) .
• Furthermore, polymorphisms in this gene may be associated with ankylosing spondylitis, insulin-dependent diabetes mellitus, celiac disease, and bronchial asthma (Li YY et al. 2014; Hang LW et al. 2003).

1. de la Salle H et al. (1999) HLA class I deficiencies.In: Ochs, H. D.; Smith, C. I. E.; Puck, J. M. (eds.): Primary Immunodeficiency Diseases: A Molecular and Genetic Approach. New York: Oxford University Press 1999: 181-188.
2. Furukawa H et al (1999) Splice acceptor site mutation of the transporter associated with antigen processing-1 gene in human bare lymphocyte syndrome. J. Clin. Invest 103: 755-758.
3. Hang LW et al (2003) TAP1 gene AccI polymorphism is associated with atopic bronchial asthma. J Clin Lab Anal17: 57-60.
4. Li YY et al. (2014) TAP1 I333V gene polymorphism and type 1 diabetes mellitus: a meta-analysis of 2248 cases. J Cell Mol Med 18:929-937.