Catalytic cycle of Enzyme I of PTS. Designations for dimer, monomer, and phosphorylated subunits are shown on the picture. Elementary processes are denoted by the arrows with numbers: processes of PEP and Pyr binding and EI phosphorylation are denoted by solid lines, dimerization (dissociation) processes are denoted by the dotted lines, and processes of the phosphate transfer to HPr denoted by the dashed lines with numbers and letter “h”. For example, there are also designations of the equilibrium constants for different types of the reactions given (description of the types see in Supplement 1. Free PEP and Pyr are not shown, numbers of the reactions of PEP, and Pyr binding are given in the Supplement 1). Lilac dashed lines: sum of the processes of singly phosphorylated dimer dissociation (Figure 2), green dashed lines: sum of the processes of the HPr phosphorylation by the doubly phosphorylated monomer (Figure 3(a)), blue dashed lines: sum of the processes of the HPr phosphorylation by the singly phosphorylated monomer (Figure 3(b)).