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Major intrinsic proteins are a large family of transmembrane protein channels that are grouped together on the basis of sequence similarities. Proteins from this family exhibit essentially two distinct types of channel properties: (1) specific water transport by the aquaporins, and (2) small neutral solutes transport, such as glycerol by the glycerol facilitators. ==Examples== MIP family includes the following channels: * Mammalian major intrinsic protein (MIP). MIP is the major component of lens fibre gap junctions. * Mammalian aquaporins.〔 These proteins form water-specific channels that provide the plasma membranes of red cells, as well as kidney proximal and collecting tubules with high permeability to water, thereby permitting water to move in the direction of an osmotic gradient. * Soybean nodulin-26, a major component of the peribacteroid membrane induced during nodulation in legume roots after Rhizobium infection. * Plants tonoplast intrinsic proteins (TIP). There are various isoforms of TIP : alpha (seed), gamma, Rt (root), and Wsi (water-stress induced). These proteins may allow the diffusion of water, amino acids and/or peptides from the tonoplast interior to the cytoplasm.. * Bacterial glycerol facilitator protein (gene glpF), which facilitates the movement of glycerol across the cytoplasmic membrane. * ''Salmonella typhimurium'' propanediol diffusion fac ilitator (gene pduF). * Yeast FPS1, a glycerol uptake/efflux facilitator protein. * Drosophila neurogenic protein 'big brain' (bib). This protein may mediate in tercellular communication; it may functions by allowing the transport of certain molecules(s) and thereby sending a signal for an exodermal cell to become an ep idermoblast instead of a neuroblast. * Yeast hypothetical protein YFL054c. * A hypothetical protein from the pepX region of ''Lactococcus lactis''. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「major intrinsic proteins」の詳細全文を読む スポンサード リンク
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