Abstract
Wheat aluminum(Al)-activated malate transporter (ALMT1) is localized on plasma membrane. Hydrophobicity profile of ALMT1 protein shows predicted 5 to 8 transmembrane regions. To elucidate the transmembrane topology of this protein, we examined the orientation of C-terminal domain of ALMT1 protein in cultured tobacco cells which expressed the ALMT1 protein tagged with the epitope at the C terminus. The accessibilities of the C terminus region of the ALMT1 protein to anti-epitope antibody and the anti-ALMT1 antiserum raised against the ALMT1 C-terminal 218 amino acid region were examined in the absence or presence of a detergent to infiltrate these antibodies into cells. The immunofluorescence signals against these primary antibodies were detected at the plasma membrane similarly in the presence or absence of the detergent. These results suggest that C terminus of ALMT1 protein faces toward the outside of the membrane.
