Gene structure of non-XIP MIPs from Populus , Arabidopsis and rice. Exon-intron organization of non-XIP MIP genes from Populus, Arabidopsis and rice is depicted for the PIP, TIP, NIP and SIP subfamilies. The exon-intron pattern observed in majority of MIPs within a subfamily is shown in gray background. In this case, only the number of MIPs having that pattern is indicated for each plant species. For example, "At:12/13" indicates that 12 out of 13 AtPIPs have the same gene structure. For those members with different exon-intron organization, the MIP name is explicitly given (example: Os:2.8 in PIP subfamily). The six TM regions are shown in black bars and the loops B and E are shown in oval shape. The intron positions are indicated by inverted triangle.