Major Facilitator Superfamily; The Major Facilitator Superfamily (MFS) is a large and diverse group of secondary transporters that includes uniporters, symporters, and antiporters. MFS proteins facilitate the transport across cytoplasmic or internal membranes of a variety of substrates including ions, sugar phosphates, drugs, neurotransmitters, nucleosides, amino acids, and peptides. They do so using the electrochemical potential of the transported substrates. Uniporters transport a single substrate, while symporters and antiporters transport two substrates in the same or in opposite directions, respectively, across membranes. MFS proteins are typically 400 to 600 amino acids in length, and the majority contain 12 transmembrane alpha helices (TMs) connected by hydrophilic loops. The N- and C-terminal halves of these proteins display weak similarity and may be the result of a gene duplication/fusion event. Based on kinetic studies and the structures of a few bacterial superfamily members, GlpT (glycerol-3-phosphate transporter), LacY (lactose permease), and EmrD (multidrug transporter), MFS proteins are thought to function through a single substrate binding site, alternating-access mechanism involving a rocker-switch type of movement. Bacterial members function primarily for nutrient uptake, and as drug-efflux pumps to confer antibiotic resistance. Some MFS proteins have medical significance in humans such as the glucose transporter Glut4, which is impaired in type II diabetes, and glucose-6-phosphate transporter (G6PT), which causes glycogen storage disease when mutated.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1831512938   6 IFNTLSVGFVGISFIAFGQIPHEHNLsAVICLGVLECFTSFSSGGFYKCGTLHARQFSSIVISAIQFTKCIALFSGPALV 85
Cdd:cd17318   276 LFTSIGFLGPGVFLIALGYLGSNATL-AVVFLTLSVGLSGACYSGFLVNHLDLAPNYAGTLMGITNTAATIAGIISPLIV 354

                          90       100       110
                  ....*....|....*....|....*....|....
gi 1831512938  86 AFFVTDESNQTQWSHVFMTLAGFTFFANILSYIY 119
Cdd:cd17318   355 GAIVKNDQTIGQWRIVFFISAAIYILGAIFYLIF 388

Solute carrier 17 (SLC17) family of the Major Facilitator Superfamily of transporters; The Solute carrier 17 (SLC17) family is primarily involved in the transport of organic anions. There are nime human proteins belonging to this family including: the type I phosphate transporters (SLC17A1-4) that were initially identified as sodium-dependent inorganic phosphate (Pi) transporters but are now known to be involved in tha transport of organic anions; lysosomal acidic sugar transporter (SLC17A5 or sialin), vesicular glutamate transporters (VGluT1#3 or SLC17A7, SLC17A6, and SLC17A8, respectively), and a vesicular nucleotide transporter (VNUT or SLC17A9). SLC17A1 and SLC17A3 have roles in the transport of urate and para-aminohippurate, respectively. The SLC17 family belongs to the Major Facilitator Superfamily (MFS) of membrane transport proteins, which are thought to function through a single substrate binding site, alternating-access mechanism involving a rocker-switch type of movement.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1831512938   6 IFNTLSVGFVGISFIAFGQIPHEHNLsAVICLGVLECFTSFSSGGFYKCGTLHARQFSSIVISAIQFTKCIALFSGPALV 85
Cdd:cd17318   276 LFTSIGFLGPGVFLIALGYLGSNATL-AVVFLTLSVGLSGACYSGFLVNHLDLAPNYAGTLMGITNTAATIAGIISPLIV 354

                          90       100       110
                  ....*....|....*....|....*....|....
gi 1831512938  86 AFFVTDESNQTQWSHVFMTLAGFTFFANILSYIY 119
Cdd:cd17318   355 GAIVKNDQTIGQWRIVFFISAAIYILGAIFYLIF 388

Solute carrier 17 (SLC17) family of the Major Facilitator Superfamily of transporters; The Solute carrier 17 (SLC17) family is primarily involved in the transport of organic anions. There are nime human proteins belonging to this family including: the type I phosphate transporters (SLC17A1-4) that were initially identified as sodium-dependent inorganic phosphate (Pi) transporters but are now known to be involved in tha transport of organic anions; lysosomal acidic sugar transporter (SLC17A5 or sialin), vesicular glutamate transporters (VGluT1#3 or SLC17A7, SLC17A6, and SLC17A8, respectively), and a vesicular nucleotide transporter (VNUT or SLC17A9). SLC17A1 and SLC17A3 have roles in the transport of urate and para-aminohippurate, respectively. The SLC17 family belongs to the Major Facilitator Superfamily (MFS) of membrane transport proteins, which are thought to function through a single substrate binding site, alternating-access mechanism involving a rocker-switch type of movement.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1831512938   6 IFNTLSVGFVGISFIAFGQIPHEHNLsAVICLGVLECFTSFSSGGFYKCGTLHARQFSSIVISAIQFTKCIALFSGPALV 85
Cdd:cd17318   276 LFTSIGFLGPGVFLIALGYLGSNATL-AVVFLTLSVGLSGACYSGFLVNHLDLAPNYAGTLMGITNTAATIAGIISPLIV 354

                          90       100       110
                  ....*....|....*....|....*....|....
gi 1831512938  86 AFFVTDESNQTQWSHVFMTLAGFTFFANILSYIY 119
Cdd:cd17318   355 GAIVKNDQTIGQWRIVFFISAAIYILGAIFYLIF 388