Three-dimensional Structure of Transporter Associated with Antigen Processing (TAP) Obtained by Single Particle Image Analysis

The transporter associated with antigen processing (TAP) is an ATP binding cassette transporter responsible for peptide translocation into the lumen of the endoplasmic reticulum for assembly with major histocompatibility complex class I molecules. Immunoaffinity-purified TAP particles comprising TAP...

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Bibliographic Details
Published in:The Journal of biological chemistry 2001-12, Vol.276 (49), p.46054-46063
Main Authors: Velarde, Giles, Ford, Robert C., Rosenberg, Mark F., Powis, Simon J.
Format: Article
Language:English
Subjects:
ABC transporter
Amino Acid Sequence
Animals
Antigens - metabolism
ATP-Binding Cassette Transporters - chemistry
ATP-Binding Cassette Transporters - isolation & purification
ATP-Binding Cassette Transporters - metabolism
Cell Line
Flow Cytometry
Protein Conformation
Rats
TAP1 protein
TAP2 protein
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Summary:The transporter associated with antigen processing (TAP) is an ATP binding cassette transporter responsible for peptide translocation into the lumen of the endoplasmic reticulum for assembly with major histocompatibility complex class I molecules. Immunoaffinity-purified TAP particles comprising TAP1 and TAP2 polypeptides, and TAP2 particles alone were characterized after detergent solubilization and studied by electron microscopy. Projection structures of TAP1+2 particles reveal a molecule ∼10 nm across with a deeply staining central region, whereas TAP2 molecules are smaller in projection. A three-dimensional structure of TAP reveals it is isolated as a single heterodimeric complex, with the TAP1 and TAP2 subunits combining to create a central 3-nm-diameter pocket on the predicted endoplasmic reticulum-lumenal side. Its structural similarity to other ABC transporters demonstrates a common tertiary structure for this diverse family of membrane proteins.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M108435200