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TAP2 gene

transporter 2, ATP binding cassette subfamily B member

Normal Function

The TAP2 gene provides instructions for making a protein that plays an important role in the immune system. The TAP2 protein assembles with another protein called TAP1 (produced from the TAP1 gene) to form a protein complex called the transporter associated with antigen processing (TAP) complex. This complex, which is found in the membrane of a cell structure called the endoplasmic reticulum, moves (transports) protein fragments (peptides) from foreign invaders into the endoplasmic reticulum. There, the peptides are attached to major histocompatibility complex (MHC) class I proteins. The peptide-bound MHC class I proteins are then moved to the surface of the cell so that specialized immune system cells can interact with them. When these immune system cells recognize the peptides as harmful, they launch an immune response to get rid of the foreign invaders.

Health Conditions Related to Genetic Changes

Bare lymphocyte syndrome type I

At least seven mutations in the TAP2 gene have been found to cause bare lymphocyte syndrome type I (BLS I). This immune system disorder often causes recurrent bacterial infections in the respiratory tract and open sores (ulcers) on the skin, although some people with BLS I have no symptoms of the condition. TAP2 gene mutations involved in BLS I prevent production of functional TAP2 protein. Absence of functional TAP2 impairs the formation of the TAP complex, without which peptides from foreign invaders cannot be transported into the endoplasmic reticulum and attached to MHC class I proteins. Consequently, MHC class I proteins are broken down, which results in a shortage of these proteins on the surface of cells. A lack of MHC class I proteins impairs the body's immune response to bacteria, leading to recurrent bacterial infections. Researchers are unsure why people with BLS I do not also get viral infections, but they suspect that other immune processes are able to recognize and fight viruses. It is also not clear how TAP2 gene mutations are involved in the development of skin ulcers.

More About This Health Condition

Other Names for This Gene

  • ABC transporter, MHC 2
  • ABC18
  • ABCB3
  • APT2
  • ATP-binding cassette, sub-family B (MDR/TAP), member 3
  • D6S217E
  • peptide supply factor 2
  • peptide transporter involved in antigen processing 2
  • peptide transporter PSF2
  • PSF-2
  • PSF2
  • RING11
  • transporter 2, ABC (ATP binding cassette)
  • transporter 2, ATP-binding cassette, sub-family B (MDR/TAP)

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Gene and Variant Databases


  • Eggensperger S, Tampe R. The transporter associated with antigen processing: a key player in adaptive immunity. Biol Chem. 2015 Sep;396(9-10):1059-72. doi: 10.1515/hsz-2014-0320. Citation on PubMed
  • Leonhardt RM, Keusekotten K, Bekpen C, Knittler MR. Critical role for the tapasin-docking site of TAP2 in the functional integrity of the MHC class I-peptide-loading complex. J Immunol. 2005 Oct 15;175(8):5104-14. doi: 10.4049/jimmunol.175.8.5104. Citation on PubMed
  • Neefjes JJ, Momburg F, Hammerling GJ. Selective and ATP-dependent translocation of peptides by the MHC-encoded transporter. Science. 1993 Aug 6;261(5122):769-71. doi: 10.1126/science.8342042. Erratum In: Science 1994 Apr 1;264(5155):16. Citation on PubMed
  • Parcej D, Tampe R. ABC proteins in antigen translocation and viral inhibition. Nat Chem Biol. 2010 Aug;6(8):572-80. doi: 10.1038/nchembio.410. Erratum In: Nat Chem Biol. 2010 Oct;6(10):782. Citation on PubMed
  • Zimmer J, Andres E, Donato L, Hanau D, Hentges F, de la Salle H. Clinical and immunological aspects of HLA class I deficiency. QJM. 2005 Oct;98(10):719-27. doi: 10.1093/qjmed/hci112. Epub 2005 Aug 8. Citation on PubMed

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.