Fig. 6.

Analysis of transcript and protein corresponding to the Gmglnβ₁ transgene in tobacco transformants. Tobacco RUB-Gmglnβ₁ and CaMV35S-Gmglnβ₁ transformants were produced using the same constructs shown in Fig. 2A. (A) Northern blot analysis of leaf RNA (10 µg) extracted from green house grown tobacco control plants and the two classes of Gmglnβ₁ transformants. Transcript was detected using a probe for the soybean GS₁ transgene (Gmglnβ₁) and EtBr stained ribosomal rRNA is shown to confirm equal loading. (B) Total soluble protein extracted from the same leaf tissue was fractionated by SDS- and native-PAGE (5 µg and 25 µg, respectively) followed by western blot analysis using anti-GS antibodies. Immunoreactive bands corresponding to GS₁ (39–40 kD) and GS₂ (42–43 kD) polypeptides and the native GS bands corresponding to the endogenous GS₂ (NtGS₂) and the transgene product (GmGS₁) are designated. (C) Transferase assay was performed on the same protein extracts as in panel B. Average values for GS activity were plotted as µmol γ-glutamyl hydroxamate produced per minute per mg of protein at 30° C. Experiments were repeated at least three times.