Exploring the minimal functional unit of the transporter associated with antigen processing.
TAP, an ABC transporter in the ER membrane, provides antigenic peptides derived from proteasomal degradation to MHC class I molecules for inspection by cytotoxic T lymphocytes at the cell surface so as to trace malignant or infected cells. To investigate the minimal number of transmembrane segments (TMs) required for assembly of the TAP complex based on hydrophobicity algorithms and alignments with other ABC transporters we generated N-terminal truncation variants of human TAP1 and TAP2. As a result, a 6+6 TM core-TAP complex represents the minimal functional unit of the transporter, which is essential and sufficient for heterodimer assembly, peptide binding, and peptide translocation into the ER. The TM1 of both, core-TAP1 and core-TAP2 are critical for heterodimerization of the complex.
Koch
Joachim
J
Institute of Biochemistry, Biocenter, Johann Wolfgang Goethe-University Frankfurt, Marie-Curie-Strasse 9, D-60439 Frankfurt a.M., Germany.
Guntrum
Renate
R
Tampé
Robert
R
D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D017951:Antigen Presentation; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000276:immunology / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000378:metabolism; D006801:Humans; D009154:Mutation; D017384:Sequence Deletion; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters; D015395:Histocompatibility Antigens Class I; C073119:TAP1 protein, human; C071692:TAP2 protein, human