Model for ER-to-cytosol transport of polyomaviruses mediated by foci formation and cytosolic SGTA.

<p>(A) Polyomaviruses become hydrophobic due to conformational changes imposed upon them by ER lumenal chaperones and PDI proteins. This hydrophobicity allows for membrane binding and integration by the viral particle. (B) Membrane-bound viruses recruit the B14-B12 complex causing their reorganization into discrete foci, which may serve to transiently increase the local concentration of chaperones at the site of membrane penetration. (C) Polyomaviruses are mobilized out of the ER into the cytosol in a SGTA-dependent manner. SGTA and Hsc70 are released from the B14-B12 complex as SGTA physically interacts with the virus.