Abstract
Recently membrane proteins which permeate water have been idnetified and named aquaporins (AQP). AQPs belong to a large membrane transport protein family called the MIP family. Members of MIP/AQP family distribute widely in almost all organisms. Their main function or role is speculated to be water transport, but rigous demonstration is lacking for most AQPs. 9 mammalian AQPs cloned to date are summarized, and current understanding of the structure of AQP is reviewed.
