Figure 2.

From sequence to structure. A: Amino acid sequence of AtSUT2 (At2g02860). Stretches of hydrophobic amino acid stretches that are predicted to be embedded into the membrane are shown in bold. B. Prediction of transmembrane topology for the sucrose transporter AtSUT2 by TmHMM v2.0. C. Schematic two-dimensional view of AtSUT2. D. Predicted 3-dimensional structure of a distant AtSUT2 homolog, the human hexose transporter GLUT1, which belongs to the MFS-family (major facilitator superfamily) (Zuniga et al., 2001). The 12 α-helical transmembrane helices are predicted to tilt slightly. E. Space filling representation of the main (in yellow) and auxiliary (in blue) substrate “pore” of GLUT1, reference as before. With kind permission from The American Society for Biochemistry and Molecular Biology. F. The functional unit of sucrose transporters may be a dimer.