Fig. 4.

Combined PS-SCL for substrate specificity of TMPRSS2, matriptase, hepsin, and HGFA. Using protease substrate terminology, the cleavage (hydrolysis) site for protease protein substrates is between the N-terminal P1 and P1′ positions of the peptide (P) substrate, while S1 and S1′ refer to the subsite (S) 1 and 1′ of the protease where the P1 and P1′ amino acid side chain binds (46). Red color designates overlap of TMPRSS2 amino acid specificity with other proteases. Single letter designations for amino acids are shown.