May be involved in membrane trafficking in the early secretory pathway. Inhibits BACE1 activity and amyloid precursor protein processing. May induce caspase-8 cascade and apoptosis. May favor BCL2 translocation to the mitochondria upon endoplasmic reticulum stress. Induces the formation of endoplasmic reticulum tubules (PubMed:25612671). Acts also as an inflammation-resolving regulator by interacting with both TRIM25 and RIG-I/DDX58, subsequently impairing DDX58 'Lys-63'-linked polyubiquitination leading to IRF3 and NF-kappa-B inhibition. (Microbial infection) Plays a positive role the viral replication and pathogenesis of enteroviruses. Homodimer. Interacts with ATL1 (By similarity). Interacts with RTN4. Isoform 3 interacts with BACE1, BACE2, BCL2 and FADD. Interacts with ATL2. Interacts with TMEM33 (By similarity). Interacts with ZFYVE27 and with KIF5A in a ZFYVE27-dependent manner (PubMed:21976701). Interacts with DDX58 (PubMed:34313226). Interacts with TRIM25 (PubMed:34313226). (Microbial infection) Interacts with Coxsackievirus A16, enterovirus 71 and poliovirus P2C proteins (PubMed:17182608). (Microbial infection) Interacts with West Nile virus protein NS4A. Isoform 3 is widely expressed, with highest levels in brain, where it is enriched in neuronal cell bodies from gray matter (at protein level). Three times more abundant in macula than in peripheral retina. Isoform 1 is expressed at high levels in brain and at low levels in skeletal muscle. Isoform 2 is only found in melanoma. By endoplasmic reticulum stress (at protein level) (PubMed:17191123). Up-regulated and self-aggregates upon RNA viral infection (PubMed:34313226). Extended N-terminus.