TMPRSS2 and infection: Shedding of a soluble form of ACE2 from the cell surface is regulated by membrane-bound enzymes such as TMPRSS2 and ADAM17.7,8 Enzymatic cleavage of the ACE2 extracellular domain by TMPRSS2 after binding of the spike protein of SARS-CoV-2 to ACE2 also plays a s role in SARS-CoV-2 cell entry and infection.