Fig. 1.

Anks1a facilitates the export of EphA2/ErbB2 complex from the ER. In serum-stimulated cells, Ser-647 and -663 of human Anks1a are the major phosphorylation sites. Serine phosphorylation may change the protein structure of Anks1a so that phosphorylated Anks1a is localized to the ER. In the ER, Anks1a interacts simultaneously with EphA2 and Sec23 via two critical motifs: the Ankyrin repeats bind to EphA2 whereas the PTB domain binds to Sec23, a component of the COPII vesicle. Then, other COPII components (i.e., Sec24 and Sec13/31) are recruited to Sec23 in the ERES, deforming ER membrane for budding and possibly competing away Anks1a. This dynamic COPII biogenesis would catalyze the selective loading of some RTK cargos into the growing COPII vesicle.