Figure 2.

Cassettes used for complementation, and transport activity of fusion proteins in Saccharomyces cerevisiae. A, Schematic representation of cassettes for tissue-specific expression of AtSUC2 cDNA (cSUC2) as the native protein and as fusions with reporter enzymes GFP and GUS (encoded by uidA). Promoters, fusions, and restriction endonuclease recognition sequences are as indicated; TGA, in-frame stop codon flanked by restriction sites for creating the native AtSUC2 protein. Reporter genes also terminate with a TGA stop codon (data not shown). The schematic is not to scale. B, Uptake of [U-¹⁴C]Suc into yeast strain SuSy7-ura3 transformed with an empty vector control (diamonds), cSUC2 (squares), and cSUC2∷uidA (crosses) expressed from the ADH1 promoter. Incubation with labeled Suc was terminated at the indicated time points, and incorporation (cpm) was determined by scintillation counting. Average and sd values from three experiments are represented.