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). Activates the host NLRP3 inflammasome, leading to IL-1beta overproduction. Homopentamer (PubMed:22819936). Interacts with membrane protein M in the budding compartment of the host cell, which is located between endoplasmic reticulum and the Golgi complex (PubMed:19322648). Interacts with Nucleoprotein (PubMed:24766657). Interacts with the accessory proteins 3a and 7a. Interacts (via C-terminus) with human PALS1 (via PDZ domain); this inhibits the interaction between human PALS1 and human CRB3, and causes delayed tight junction formation and defective cell polarity (PubMed:20861307). Colocalizes with S in the host endoplasmic reticulum-Golgi intermediate compartment (PubMed:20861307). The cytoplasmic tail functions as a Golgi complex-targeting signal. Belongs to the betacoronaviruses E protein family.