Figure 5.

Effect of in vivo blue light irradiation on in vitro light-dependent phot1 kinase activity. Total protein extracts were made from 3-day-old etiolated seedlings maintained in darkness (D) or given one of three different in vivo blue-light treatments: 0.5 μmol m⁻² s⁻¹ for 30 min (Low Blue), 20 μmol m⁻² s⁻¹ for 15 min (High Blue), or 20 μmol m⁻² s⁻¹ for 15 min followed by 0.5 μmol m⁻² s⁻¹ for 30 min (High Blue + Low Blue). (A) Autoradiograph of in vitro kinase assays of total protein extracts given an in vitro mock irradiation (D) or irradiated with white light (L) at a total fluence of 30,000 μmol m⁻² upon addition of radiolabeled ATP. Immunoblot analysis of protein levels with anti-phot1 antibody and anti-UGPase antibody as a loading control is shown in the lower panel. (B) Quantification of in vitro light-dependent phot1 kinase activity in total protein extracts. Kinase activity was quantified and expressed as a percentage of maximal autophosphorylation.