Human coronaviruses are pathogens that can cause serious respiratory tract infections. SARS-CoV-2 is a new human coronavirus characterized in 2020 and causes “coronavirus disease 2019” or “COVID-19” (Xu et al. 2020). The four major structural proteins of SARS-CoV-2 are peak glycoprotein (S), membrane matrix protein (M), nucleocapsid protein (N), and envelope protein (E) ( Duart et al. 2020).
The envelope protein plays a role in compromising the integrity of host membranes and forming membrane compartments in which the virus replicates (Mukherjee et al. 2020).
It forms a homopentameric cation channel that mediates the budding and release of progeny viruses and activates the host’s inflammasome. Removal of the envelope protein attenuates some coronaviruses, and the envelope protein has been suggested as a potential target for drugs and vaccines (Mandala et al. 2020).
The envelope protein of SARS-CoV-2 is one of the four main structural proteins of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of COVID-19 (1). The envelope protein is the smallest of the four structural proteins, which also includes the membrane protein, the spike protein, and the nucleocapsid protein (1,2). The envelope protein is synthesized as a 75 amino acid protein with a theoretical molecular weight of approximately 8.4 kDa (2,3).
Furthermore, the SARS-CoV-2 envelope protein has 94.7% sequence identity and 97.4% sequence similarity to the SARS-CoV envelope protein (2). Structurally, the envelope protein is a membrane protein with an N-terminal domain, an alpha-helix transmembrane domain, and a hydrophilic C-terminal domain.
The envelope protein has multiple roles in viral replication, including viral assembly, release, and pathogenesis (2,4). Furthermore, the envelope protein of SARS-CoV-2 has ion channel activity and functions as a viroporin with a role in virion trafficking (2,4). Coronaviruses lacking the envelope protein have been shown to have low viral titer and slow or defective maturation, indicating a role in virus production and growth.