Aquaporins are membrane proteins that regulate the plant water balance by acting as water channel. Plant aquaporins are part of the large family of MIPs (major intrinsic proteins) , which is subdivided into plasma membrane (PIP) , tonoplast (TIP) , nodulin-like (NIP) , small basic (SIP) intrinsic proteins and the newly identified, as yet unlocalized XIPs. TIP2;2 (AT4G17340) is one of the TIP protein family. TIP2;3 (AT5G47450) shows 81% identity with TIP2;2.
