Component of the ERLIN1/ERLIN2 complex which mediates the endoplasmic reticulum-associated degradation (ERAD) of inositol 1,4,5-trisphosphate receptors (IP3Rs). Involved in regulation of cellular cholesterol homeostasis by regulation the SREBP signaling pathway. Binds cholesterol and may promote ER retention of the SCAP-SREBF complex (By similarity). Forms a heteromeric complex with ERLIN2 (By similarity). In complex with ERLIN2, interacts with RNF170 (PubMed:21610068). Interacts with AMFR and SYVN1 (By similarity). Associated with lipid raft-like domains of the endoplasmic reticulum membrane. Belongs to the band 7/mec-2 family. Truncated N-terminus. Truncated N-terminus.