Figure 2. AtG3BP1 is expressed and localized to different cellular compartments.

(A) Expression patterns for the GUS reporter gene under the control of the AtG3BP1 promoter in transgenic Arabidopsis seedlings. Histochemical GUS staining at the seedling stage. (i) 8-d-old seedling stained for 2 h. (ii) Shoot apical meristem of 14-d-old seedling stained for 12 h. (iii) Lateral root of 14-d-old seedling stained for 8 h. (iv) Root apical meristem of 12-d-old seedlings stained for 2 h. Scale bar: (i) = 1,000 μm, (ii–iv) = 20 μm. (B) Immunoblot of WT, OE2 plants expressing 35S::AtG3BP1–GFP probed with anti-GFP antibody (upper panel) and protein loading control with Ponceau S staining (lower panel). (C) AtG3BP1 expression and protein localization in Arabidopsis roots (8 d) and leaves (12 d). Stable transgenic plants overexpressing AtG3BP1–GFP (OE2) reveal that AtG3BP1 is mainly localized to various cytoplasmic compartments. Confocal laser scanning microscopy images of GFP fluorescence (green) and propidium iodide (PI) fluorescence (red) of Arabidopsis seedlings in the (i) shoot apical meristem, (ii) leaf epidermis, and (iii) hypocotyl. Panel (iv) is the enlargement of boxed area in (iii), showing details of stomata localization. (v) Root apical meristem–epidermal layer. Panel (vi) is the enlargement of boxed area in (v), showing details of localization of AtG3BP1 to cytoplasmic compartments and structures. The protein is excluded from the nucleus. (vii, viii) Root differentiation zone. Scale bar: 20 μm. (D) Subcellular localization of transiently expressed 35S::AtG3BP1–GFP and pUBi::Serrate–CFP in N. benthamiana cells. The indicated combinations of fluorescently tagged proteins were transiently expressed in 4-week-old N. benthamiana leaf epidermal cells. The localization was visualized 72 h after infiltration by laser scanning confocal microscopy. GFP fluorescence is in green and CFP fluorescence is in blue. Scale bars = 20 μm.