Figure 4.

GPT1 Interacts with Cytosolic Oxidoreductases Trx_h7 and Grx_c1 at the ER.

(A) and (B) Localization of GPT1 upon interaction with Trx_h7 or Grx_c1 in Arabidopsis protoplasts (24- to 48-h post transfection). The schemes illustrate different orientation of the candidate proteins with respect to free N- and C-terminal ends. GPT1 interacts with both oxidoreductases (green signals) at the ER and its spherical substructures (arrowheads), except when the N terminus of Grx_c1 is masked (B, c and d). Note that these substructures differ from those labeled in Figure 3B. Merge of BiFC signals (green) with the ER marker (OFP-ER) or peroxisome marker (Per, OFP-PGL3_C-short) is shown in magenta, and chlorophyll fluorescence is shown in blue. Scale bars = 3 μm.

(C) and (D) Localization of split YFP reconstitution (BiFC, yellow signals) in heterologous tobacco protoplasts (24- to 48-h post transfection), testing a potential effect of the other oxidoreductase (co-expressed as OFP fusion, magenta). Note that similar ER substructures are labeled (merged, single sections). All other images show maximal projections of ∼30 optical sections. Chlorophyll fluorescence is shown in blue. Co-localization and very close signals (<200 nm) appear white in the merge of all channels. Scale bars = 3 μm.