Phylogeny of Major Intrinsic Proteins

Major intrinsic proteins (MIPs) form a large superfamily of proteins that can be divided into different subfamilies and groups according to phylogenetic analyses. Plants encode more MIPs than other organisms and seven subfamilies have been defined, whereof the Nodulin26-like major intrinsic proteins (NIPs) have been shown to permeate metalloids. In this chapter we review the phylogeny of MIPs in general and especially of the plant MIPs. We also identify bacterial NIP-like MIPs and discuss the evolutionary implications of this finding regarding the origin and ancestral transport specificity of the NIPs.