The Major Intrinsic Protein

The Major Intrinsic Proteins (MIPs) constitute a large group of transmembrane channels involved in the specific transport of water, and/or small solutes across the lipid bilayer. Since water is the most abundant molecule in all living organisms, the discovery of selective water-transporting channels called AQPs (aquaporins) has led to new knowledge on both the physiological and molecular mechanisms of membrane permeability.

The Major Intrinsic Protein database

MIPs are identified in Archaea, Bacteria and Eukaryota. The explosive growth of MIP sequences in general databases is suitable for large-scale studies in comparative genomics as well as in phylogeny. Unfortunately, the quality/quantity ratio of these data is generally low and can greatly affect the interpretation of computational studies. We think that specialized databases have some advantages if they are developped for and by their principal users in molecular biology and bioinformatics. Therefore, we developed MIPdb (database for Major Intrinsic Proteins), dedicated to inventory, classification and curation of MIPs. In MIPdb, we use a hierarchical functional classification of type, superfamily > family > subfamily. MIP is used for the superfamily term. There are three functional families which are respectively highly selective water channels (orthodox aquaporin, AQPs), channels permeable both to water and to small amphipathic molecules (aquaglyreroporins, GLAs), and solute transporters without water permeability of physiologically significant (orthodox glyceroporins, GLPs). The subfamily term is dedicated to clusters of proteins linked at a more specific level, for instance the intracellular localisation. Subfamilies names and acronyms are widely used for plant MIPs : plasma membrane intrinsic proteins (PIPs), tonoplast membrane intrinsic proteins (TIPs), small basic intrinsic proteins (SIPs), nodulin-like intrinsic proteins (NIPs), glycerol-facilitator-like intrinsic proteins (GIPs), X-intrinsc proteins (XIPs), hybrid intrinsic proteins (HIPs).

MIPdb team (August 2011)

MIPdb was designed and developped by C. Delamarche and A. Le Bechec.
A. Muller, A. Talvas, S. Prigent and P. Gloaguen participated in the developpement of the interface and programmed some parts of the pipeline for protein classification. I. Stevant realised the logo of the database.

Please feel free to contact MIPdb team for any questions, comments and suggestions.