Molecular adapter that stimulates membrane curvature formation and subsequent endoplasmic reticulum exit site (ERES) establishment by recruiting PI3K complex I, leading to COPII vesicle-mediated transport (PubMed:32690950). Promotes endoplasmic reticulum (ER) exit of cGAMP-activated STING1 oligomers (PubMed:32690950, PubMed:37832545).