Table 1.

Role of the effector and insert regions of Rac in the hysteretic coupling of the Rac redox response and NOX2 activation

Rac		Hyperbolic NOX2 activation with fully preactivated Rac	Hysteretic Rac activation with initially inactive Rac	Hysteretic NOX2 activation with initially inactive Rac	Hyperbolic Rac activation with fully preactivated Rac	Rac redox sensitivitya
wt Rac		+++	+++	+++	+++	+++
Rac redox motif mutants	C18S	—	—	—	+++	—
	C157S	—	—	—	+++	—
Rac effector region mutants	A27K	—	—	—	—	+++
	G30S	—	—	—	—	+++
Rac insert region mutants	K132E	++	++	++	++	+++
	L134R	++	++	++	++	+++

^aRac redox sensitivity was measured without the NOX2 phox complex in the cell-free system by using KO₂ as the O₂⁻ source. The symbol “+++” represents the maximal wt Rac redox sensitivity or the fastest hysteretic activation rate of NOX2 and wt Rac over time based upon the results shown in Figure 2, A and B. The symbols “++” and “+” reflect, respectively, 30% and 60% slower rates than those of the rates shown as “+++.” The symbol “—” denotes a lack of the redox sensitivity or hysteretic activation over time.