HMM Summary Page: TIGR00861

FunctionMIP family channel proteins
Trusted Cutoff171.25
Domain Trusted Cutoff171.25
Noise Cutoff123.00
Domain Noise Cutoff123.00
Isology Typesubfamily
HMM Length224
Mainrole CategoryTransport and binding proteins
Subrole CategoryUnknown substrate
AuthorPaulsen IT, Saier MH, Loftus BJ
Entry DateAug 11 2000 1:26PM
Last ModifiedFeb 14 2011 3:27PM
Comment1.A.8 The Major Intrinsic Protein (MIP) Family The MIP family is large and diverse, possessing over 100 members that all form transmembrane channels. These channel proteins function in water, small carbohydrate (e.g., glycerol), urea, NH3, CO2 and possibly ion transport by an energy independent mechanism. They are found ubiquitously in bacteria, archaea and eukaryotes. The MIP family contains two major groups of channels: aquaporins and glycerol facilitators. The known aquaporins cluster loosely together as do the known glycerol facilitators. MIP family proteins are believed to form aqueous pores that selectively allow passive transport of their solute(s) across the membrane with minimal apparent recognition. Aquaporins selectively transport water (but not glycerol) while glycerol facilitators selectively transport glycerol but not water. Some aquaporins can transport NH3 and CO2. Glycerol facilitators function as solute nonspecific channels, and may transport glycerol, dihydroxyacetone, propanediol, urea and other small neutral molecules in physiologically important processes. Some members of the family, including the yeast FPS protein (TC #1.A.8.5.1) and tobacco NtTIPA may transport both water and small solutes.
ReferencesSE Ipaulsen AL clustalw_manual DR HAMAP; MF_01146; 26 of 27