Enables several functions, including ATP hydrolysis activity; TAP binding activity; and adenyl ribonucleotide binding activity. Contributes to peptide antigen binding activity. Involved in peptide transport and protection from natural killer cell mediated cytotoxicity. Located in intracellular membrane-bounded organelle. Part of TAP complex. Human ortholog(s) of this gene implicated in several diseases, including MHC class I deficiency; autoimmune disease (multiple); bronchial disease (multiple); diffuse scleroderma; and lung disease (multiple). Orthologous to human TAP1 (transporter 1, ATP binding cassette subfamily B member). [provided by Alliance of Genome Resources, Apr 2022]