Inhibits amyloid precursor protein processing, probably by blocking BACE1 activity (PubMed:15286784). Enhances trafficking of the glutamate transporter SLC1A1/EAAC1 from the endoplasmic reticulum to the cell surface (By similarity). Plays a role in the translocation of SLC2A4/GLUT4 from intracellular membranes to the cell membrane which facilitates the uptake of glucose into the cell (By similarity). Interacts with isoform 1 but not isoform 3 of SPAST (PubMed:22232211). Interacts with BACE1 (PubMed:15286784). Interacts (via first transmembrane domain) with ARL6IP5/GTRAP3-18 (By similarity). Interacts (via N-terminus) with SLC1A1/EAAC1; the interaction promotes cell surface expression of SLC1A1 (By similarity). Interacts with TMEM33. Localizes to intermediate filaments in mononucleated myoblasts and to Z lines in mature myotubes. Highly expressed in skeletal muscle. The disease is caused by variants affecting the gene represented in this entry. Produced by alternative initiation at Met-341 of isoform RTN2-A.