Fig. 3.

CrGUN4 stimulation of MgCh turnover is enhanced by bilins. (A) Comparative kinetics of MgCh activity varying CHLH1 in the presence of GUN4 alone or GUN4 with PCB. [PPIX] = 2 µM. (B) GUN4 stimulation of MgCh at 2,000 nM PCB, 500 nM CHLH1, and 1 µM PPIX, activity at 0 nM GUN4 = 0.013 ± 0.007 MgPPIX min⁻¹. (C) Stimulation of MgCh activity at increasing concentration of bilins (PCB and BV) in the presence of GUN4; 500 nM CHLH1 and 1,000 nM PPIX, activity at 0 nM bilin = 0.037 ± 0.009 MgPPIX min⁻¹. (D) Effect of increasing PCB concentration on MgCh at two different GUN4:PCB ratios with 1,000 nM CHLH1, activity at 0 nM PCB = 0.050 ± 0.018 MgPPIX min⁻¹. Values are means ± SD of three technical replicates in all panels.