isoform 1 is encoded by transcript variant 1; antigen peptide transporter 2; peptide supply factor 2; peptide transporter PSF2; ABC transporter; MHC 2; transporter 2; ABC (ATP binding cassette); ATP-binding cassette; sub-family B (MDR/TAP); member 3; go_component: cytosol; go_component: TAP complex; go_component: cytosol; go_component: TAP complex; go_component: integral to membrane; go_component: integral to membrane; go_component: endoplasmic reticulum lumen; go_component: endoplasmic reticulum lumen; go_function: ATP binding; go_function: ATP binding; go_function: ATP binding; go_function: ATPase activity; go_function: tapasin binding; go_function: phosphate binding; go_function: nucleotide binding; go_function: tapasin binding; go_function: transporter activity; go_function: phosphate binding; go_function: peptide antigen binding; go_function: transporter activity; go_function: MHC class I protein binding; go_function: peptide antigen binding; go_function: MHC class I protein binding; go_function: homoaconitate hydratase activity; go_function: oligopeptide transporter activity; go_function: protein heterodimerization activity; go_function: homoaconitate hydratase activity; go_function: protein heterodimerization activity; go_function: peptide antigen-transporting ATPase activity; go_function: peptide antigen-transporting ATPase activity; go_function: ATPase activity; coupled to transmembrane movement of substances; go_process: immune response; go_process: peptide transport; go_process: oligopeptide transport; go_process: cytosol to ER transport; go_process: protein complex assembly; go_process: cytosol to ER transport; go_process: protein complex assembly; go_process: intracellular protein transport; go_process: intracellular protein transport; go_process: antigen presentation; endogenous peptide antigen; go_process: antigen presentation; endogenous peptide antigen; go_process: antigen processing; endogenous antigen via MHC class I; go_process: antigen processing; endogenous antigen via MHC class I