Figure 4

Schematic representation of the predicted exon-intron structures of the Arabidopsis AQP genes. The general layout of the coding regions of an AQP gene is shown, with the six transmembrane domains denoted H1-H6, and the interhelical loops in white. LB and LE identify hydrophobic, pore-forming loops that include an NPA motif. The location of the introns for each AQP subfamily is shown by colored arrows: PIPs, blue; TIPs, green; NIPs, gold; and SIPs, red. Each subfamily is characterized by the number of introns and the locations of their insertion in the coding regions. Exceptions are indicated by the following symbols. *, Intron absent from TIP2;2, TIP2;3, TIP1;1, TIP1;2 and TIP1;3. **, Intron absent from TIP1;3. +, Sliding intron in PIP2;4 (appears where intron 2 in TIPs is typically found.). ++, Intron absent from NIP2;1 and NIP5;1. #, Intron absent from NIP3;1.