Fig. 4.

Localization of AtALMT12. The AtALMT12 coding sequence–GFP (ORF::GFP) construct under the control of the 35S promoter was transiently expressed in onion epidermal cells (A–O) and V. faba guard cells (P–V). As control, GFP alone was expressed in onion cells (A–C) or V. faba cells (P–R). Expression of GFP::AtALMT12 (N-terminal fusion, D–F) or AtALMT12::GFP (C-terminal fusion, G–I) shows similar localizations in onion cells. GFP fluorescence surrounds the nucleus, suggesting that AtALMT12 localized to both endomembranes and plasma membrane (J–L). Plasmolysis of AtALMT12::GFP-expressing cells with 1 M mannitol shows that the Hechtian strands attaching the plasma membrane to the cell wall are labeled, confirming that the protein is localized on the plasma membrane. Co-expression of AtALMT12::GFP with Cyt b5::mRFP as an ER marker (S–V). Fluorescence from AtALMT12::GFP co-localized with Cyt b5::mRFP suggests that AtALMT12 is targeted to the ER. Photographs show GFP fluorescence images (A, D, G, J, M, P, S), mRFP images (T), transmitted light images (C, I, L, O, R, V) and merged images (B, E, H, K, N, Q, U).