The syp121 Mutation Does Not Affect K+ Channel Mobility at the Cell Periphery Assessed by FRAP and FLIP in Arabidopsis syp121 Mutant Root Hairs.
(A) and (B) AKT1-GFP FLIP in an Arabidopsis syp121-1 mutant root hair.
(A) Bright-field and fluorescence image taken before (top two frames) and at times during repetitive photobleaching (start of photobleach cycles, relative t = 0) at the distal end of the root hair (photobleach area indicated in the first fluorescence image). See Supplemental Movie 3 online for full image sequence.
(B) FLIP analysis of the fluorescence signals taken from the regions indicated (inset, green and red boxes) and corrected for background fluorescence decay shows a limited loss of signal outside the area of photobleaching (photobleach periods indicated by gray bars). The solid curve is the result of nonlinear least squares fitting of the postbleach fluorescence signal to a single exponential function yielding an immobile fraction of 0.84. Similar results were obtained in each of four separate experiments with the syp121 mutant and in four experiments with wild-type seedlings and KC1-YFP in place of AKT1-GFP. Bar = 10 μm.
(C) and (D) AKT-GFP FRAP in an Arabidopsis syp121-1 mutant root hair.
(C) Bright-field and fluorescence image taken before (top two frames) and after photobleaching (end of photobleach, relative t = 0) the distal end of the root hair (photobleach areas indicated in the first fluorescence image). See Supplemental Movie 2 online for full image sequence.
(D) FRAP analysis of the fluorescence signals taken from the regions indicated (inset, green and red boxes) and corrected for background fluorescence decay shows the loss of signal after photobleaching and its limited recovery. Photobleach time indicated by gray bar. The solid curve is the result of nonlinear least squares fitting of the postbleach fluorescence signal to a single exponential function. Similar results were obtained in each of eight separate experiments with the syp121 mutant and in seven experiments with wild-type seedlings, yielding immobile fractions of 0.86 ± 0.04 and 0.84 ± 0.03, respectively. Bar = 10 μm.