The first N-terminal transmembrane helix of each subunit of the antigenic peptide transporter TAP is essential for independent tapasin binding - PubMed (original) (raw)

. 2006 Jul 24;580(17):4091-6.

doi: 10.1016/j.febslet.2006.06.053. Epub 2006 Jun 30.

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The first N-terminal transmembrane helix of each subunit of the antigenic peptide transporter TAP is essential for independent tapasin binding

Joachim Koch et al. FEBS Lett. 2006.

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Abstract

The heterodimeric ABC transporter TAP translocates proteasomal degradation products from the cytosol into the lumen of the endoplasmic reticulum, where these peptides are loaded onto MHC class I molecules by a macromolecular peptide-loading complex (PLC) and subsequently shuttled to the cell surface for inspection by cytotoxic T lymphocytes. Tapasin recruits, as a central adapter protein, other components of the PLC at the unique N-terminal domains of TAP. We found that the N-terminal domains of human TAP1 and TAP2 can independently bind to tapasin, thus providing two separate loading platforms for PLC assembly. Moreover, tapasin binding is dependent on the first N-terminal transmembrane helix of TAP1 and TAP2, demonstrating that these two helices contribute independently to the recruitment of tapasin and associated factors.

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