Characterization of the angiotensin-converting enzyme 2 (ACE2), the main receptor for the SARS-CoV-2 virus

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes Coronavirus Disease 2019 (COVID-19), one of the deadliest medical difficulties to affect people in more than a century. The virus has now spread to many countries worldwide, posing a big challenge to the health status of people in affected populations. Gaining more knowledge about the different aspects of this virus will lead us to better control and treatment methods. In this paper, we discuss the SARS-CoV-2 structure and the mechanism of this virus's entry into host cells through angiotensin-converting enzyme 2 (ACE2), the main receptor for the SARS-CoV-2 virus. The main connection between SARS-CoV-2 and ACE2 is Spike protein. Other topics are also included, like ACE2 structure, functions, and physiology. For instance, ACE2 is involved in the renin-angiotensin-aldosterone system, Angiotensin A/ACE2/Alamandine/MAS-Related GPCR D (MrgD) Axis, the Kinin-Kallikrein System. It also acts as Chaperone Protein for the Amino Acid Transporter, B0AT1, and has a connection with Apelin Peptides. Since ACE2 plays a primary role in COVID-19 pathogenesis, scientists have discovered some SARS-CoV-2 therapy methods based on ACE2 targeting. Tissue expression in different genders and ages, polymorphisms, and host epigenetics, the role of ACE2 in hypertension, and cytokine storm are explained separately.