In DCs subset of ER proteins including MHC-I peptide loading complex (PLC) and transporter associated with antigen processing (TAP) transit to phagosomes via the intermediate compartment ER-Golgi intermediate compartment (ERGIC) (Cebrian et al. 2011). TAP exits the ER in COPII vesicles in association with MHC class I, and that peptide translocation by TAP and binding to class I can occur in post-ER compartments (Ghanem et al. 2010). SEC22B, an ER-resident SNARE is required for the transport of PLC from ERGIC (Cebrian et al. 2011), but this step does not deliver MHC-I (Nair-Gupta et al. 2014). Instead, MHC-I are recruited from an endosomal recycling compartment (ERC), which is marked by Rab11a, VAMP3/cellubrevin, and VAMP8/endobrevin that holds large reserves of MHC-I. This step is dependent on TLR signalling (Nair-Gupta et al. 2014).
Nair-Gupta, P, Baccarini, A, Tung, N, Seyffer, F, Florey, O, Huang, Y, Banerjee, M, Overholtzer, M, Roche, PA, Tampé, R, Brown, BD, Amsen, D, Whiteheart, SW, Blander, JM
Cebrian, I, Visentin, G, Blanchard, N, Jouve, M, Bobard, A, Moita, C, Enninga, J, Moita, LF, Amigorena, S, Savina, A
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