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The solute carrier (SLC) group of membrane transport proteins include over 300 members organized into 52 families. Most members of the SLC group are located in the cell membrane. The SLC gene nomenclature system was originally proposed by the HUGO Gene Nomenclature Committee (HGNC) and is the basis for the official HGNC names of the genes that encode these transporters. A more general transmembrane transporter classification can be found in TCDB database. Solutes that are transported by the various SLC group members are extraordinarily diverse and include both charged and uncharged organic molecules as well as inorganic ions and the gas ammonia. As is typical of integral membrane proteins, SLCs contain a number of hydrophobic transmembrane alpha helices connected to each other by hydrophilic intra- and extra-cellular loops. Depending on the SLC, these transporters are functional as either monomers or obligate homo- or hetero-oligomers. ==Scope== By convention of the nomenclature system, members within an individual SLC family have greater than 20-25% sequence homology to each other. In contrast, the homology between SLC families is very low to non-existent. Hence, the criteria for inclusion of a family into the SLC group is not evolutionary relatedness to other SLC families but rather functional (i.e., an integral membrane protein that transports a solute). The SLC group include examples of transport proteins that are: * facilitative transporters (allow solutes to flow downhill with their electrochemical gradients) * secondary active transporters (allow solutes to flow uphill against their electrochemical gradient by coupling to transport of a second solute that flows downhill with its gradient such that the overall free energy change is still favorable) The SLC series does not include members of transport protein families that have previously been classified by other widely accepted nomenclature systems including: * primary active transporters (allow flow uphill against electrochemical gradients) such as ABC (ATP Binding Cassette) transporters by coupling transport to an energy releasing event such as ATP hydrolysis * ion channels * aquaporins (water channels) 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「Solute carrier family」の詳細全文を読む スポンサード リンク
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