Isoform vMIA sequesters proapoptotic BAX at the outer mitochondrial membrane and prevents cytochrome c release and subsequent initiation of the proapoptotic cascade. Also provoques a calcium efflux from host endoplasmic reticulum and F-actin cytoskeleton disruption. Participates in the increase of host mitochondrial biogenesis, thus promoting viral replication by efficient use of newly made mitochondria. Isoform gpUL37 may play a role in escape from the host antiviral response. Isoform vMIA interacts with host BAX. Isoform vMIA interacts with host RSAD2/viperin; this interaction results in RSAD2/viperin relocalization from the endoplasmic reticulum to the mitochondria, actin cytoskeleton disruption and enhancement of infection. The C-terminal fragment localizes to the endoplasmic reticulum while the N-terminal fragment is stable and traffics to mitochondria. Transported from the endoplasmic reticulum (ER) through the mitochondrial associated membrane (MAMs) to the mitochondrial outer membrane. Associates with internal lipid rafts (LRs) in the MAM. Not cleaved or N-glycosylated. Belongs to the immediate early glycoprotein family.