Plays a central role in virus morphogenesis and assembly. Acts as a viroporin and self-assembles in host membranes forming pentameric protein-lipid pores that allow ion transport. Also plays a role in the induction of apoptosis (By similarity). Regulates the localization of S protein at cis-Golgi, the place of virus budding (PubMed:33229438). May act by slowing down the cell secretory pathway (PubMed:33229438). May interfere with tight-junction stability by interacting with host MPP5. This would result in disruption of epithelial barriers, thereby amplifying inflammatory processes (PubMed:32891874). Homopentamer (PubMed:33177698). Interacts with membrane protein M in the budding compartment of the host cell, which is located between endoplasmic reticulum and the Golgi complex. Interacts with Nucleoprotein (By similarity). Interacts with the accessory proteins 3a and 7a (By similarity). Interacts (via C-terminus) with human MPP5 (via PDZ domain); this inhibits the interaction between human MPP5 and human CRB3, and causes disruption of epithelial cells tight junctions (PubMed:32891874). The cytoplasmic tail functions as a Golgi complex-targeting signal. Variant Omicron/BA.1 and BA.2 belong to a lineage first isolated in South Africa (November 2021). Belongs to the betacoronaviruses E protein family.