Fig. 4.

Differential PIN targeting to the lytic vacuole during plant development. (A and B) Increased PIN2 targeting to the vacuole in epidermal cells at the upper root side in contrast to the symmetric vacuolar signal in vertically grown roots (A) after dark treatment of gravistimulated (for 3 h) PIN2-GFP roots (B). (C) Differential down-regulation of PIN2-GFP in upper epidermal cells after gravitropic stimulus for 3 h in snx1 mutant seedlings. (D) Enhanced gravity-induced degradation of PIN2 in snx1 mutants revealed by quantitative time course of total PIN2 protein abundance after gravity stimulation. Arrowheads mark differential PIN degradation in lytic vacuoles.