Targets proteins containing a FFAT motif to endoplasmic reticulum membranes. Regulates phospholipid biosynthesis by modulating the subcellular localization of the transcriptional repressor OPI1. Interacts with OPI1. The MSP domain is required for binding to the FFAT motif of target proteins. Present with 3497 molecules/cell in log phase SD medium. Belongs to the VAMP-associated protein (VAP) (TC 9.B.17) family.