Acts as an ER-phagy receptor required for the selective autophagic degradation of endoplasmic reticulum (ER) fragments to maintain ER homeostasis and restrain ER stress-induced inflammatory responses (PubMed:39284914). Its function depends on phosphorylation- induced dimerization, which enhances interaction with GABARAP and facilitates recruitment of ER fragments to autophagosomes (PubMed:39284914). Restricts trafficking of FAF2 from the endoplasmic reticulum to lipid droplets (PubMed:23297223). In association with LMBR1L and E3 ubiquitin-protein ligase AMFR, negatively regulates the canonical Wnt signaling pathway in the lymphocytes by promoting the ubiquitin-mediated degradation of CTNNB1 and Wnt receptors FZD6 and LRP6 (PubMed:31073040). {ECO:0000269|PubMed:23297223, ECO:0000269|PubMed:31073040, ECO:0000269|PubMed:39284914}. This is the function of UBAC2 (UBA domain containing 2, Ensembl gene identifier ENSG00000134882).