TAP2 gene

The TAP2 gene provides instructions for creating a protein essential to the immune system's ability to identify and eliminate foreign invaders.

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.

• Mechanism:TAP2 gene mutations involved in BLS I prevent production of functional TAP2 protein.
• Impact: 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.
• Consequence: 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.

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)