Solute carrier family

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The SoLute Carrier (SLC) group of membrane transport proteins include over 300 members organized into 47 families.[1] The SLC gene nomenclature system was originally proposed by the Human Genome Organization (HUGO) and is the basis for the official HUGO names of the genes that encode these transporters.

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.

As is typical of integral membrane proteins, SLCs contain a number of hydrophobic transmembrane alpha helices connected to each other by hydrophilic intra- or extra-cellular loops. Depending on the SLC, these transporters are functional as either monomers or obligate homo- or hetero-olgiomers.


By convention of the nomenclature system, members within an individual SLC family have greater than 20% 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 which transports a solute).

The SLC group include examples of transport proteins that are:

The SLC series does not include members of transport protein families which have previously been classified by other widely accepted nomenclature systems including:

Subcellular distribution

Most members of the SLC group are located in the outer cell membrane, but some members are located in mitochondria (most notably SLC family 25) or other intracellular organelles.

Nomenclature system

Names of individual SLC members have the following format:

  • SLCnXm

where n = an integer representing a family (e.g., 1-47),
X = a single letter (A, B, C, ...) denoting a subfamily, and
m = an integer representing an individual family member (isoform).

For example SLC1A1 is the first isoform of subfamily A of SLC family 1.

An exception occurs with SLC family 21 (the organic anion transporting polypeptide transporters) which for historical reasons have names in the format SLCOnXm where n = family number, X = subfamily letter, and m = member number.

While the HUGO nomenclature system by definition only includes human genes, the nomenclature system has been informally extended to include rodent species through the use of lower cases letters (e.g., Slc1a1 denotes the rodent ortholog of the human SLC1A1 gene).



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  19. Eiden LE, Schafer MK, Weihe E, Schutz B (2004). "The vesicular amine transporter family (SLC18): amine/proton antiporters required for vesicular accumulation and regulated exocytotic secretion of monoamines and acetylcholine". Pflugers Arch. 447 (5): 636–640. doi:10.1007/s00424-003-1100-5. PMID 12827358.
  20. Ganapathy V, Smith SB, Prasad PD (2004). "SLC19: the folate/thiamine transporter family". Pflugers Arch. 447 (5): 641–646. doi:10.1007/s00424-003-1068-1. PMID 14770311.
  21. Collins JF, Bai L, Ghishan FK (2004). "The SLC20 family of proteins: dual functions as sodium-phosphate cotransporters and viral receptors". Pflugers Arch. 447 (5): 641–646. doi:10.1007/s00424-003-1088-x. PMID 12759754.
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  25. Schnetkamp PP (2004). "The SLC24 Na+/Ca2+-K+ exchanger family: vision and beyond". Pflugers Arch. 447 (5): 683–688. doi:10.1007/s00424-003-1069-0. PMID 14770312.
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  28. Stahl A (2004). "A current review of fatty acid transport proteins (SLC27)". Pflugers Arch. 447 (5): 722–727. doi:10.1007/s00424-003-1106-z. PMID 12856180.
  29. Gray JH, Owen RP, Giacomini KM (2004). "The concentrative nucleoside transporter family, SLC28". Pflugers Arch. 447 (5): 728–734. doi:10.1007/s00424-003-1107-y. PMID 12856181.
  30. Baldwin SA, Beal PR, Yao SY, King AE, Cass CE, Young JD (2004). "The equilibrative nucleoside transporter family, SLC29". Pflugers Arch. 447 (5): 735–743. doi:10.1007/s00424-003-1103-2. PMID 12838422.
  31. Palmiter RD, Huang L (2004). "Efflux and compartmentalization of zinc by members of the SLC30 family of solute carriers". Pflugers Arch. 447 (5): 744–751. doi:10.1007/s00424-003-1070-7. PMID 12748859. line feed character in |title= at position 74 (help)
  32. Petris MJ (2004). "The SLC31 (Ctr) copper transporter family". Pflugers Arch. 447 (5): 752–755. doi:10.1007/s00424-003-1092-1. PMID 12827356.
  33. Gasnier B (2004). "The SLC32 transporter, a key protein for the synaptic release of inhibitory amino acids". Pflugers Arch. 447 (5): 752–755. doi:10.1007/s00424-003-1091-2. PMID 12750892.
  34. Hirabayashi Y, Kanamori A, Nomura KH, Nomura K (2004). "The acetyl-CoA transporter family SLC33". Pflugers Arch. 447 (5): 760–762. doi:10.1007/s00424-003-1071-6. PMID 12739170.
  35. Murer H, Forster I, Biber J (2004). "The sodium phosphate cotransporter family SLC34". Pflugers Arch. 447 (5): 763–767. doi:10.1007/s00424-003-1072-5. PMID 12750889.
  36. Ishida N, Kawakita M (2004). "Molecular physiology and pathology of the nucleotide sugar transporter family (SLC35)". Pflugers Arch. 447 (5): 768–775. doi:10.1007/s00424-003-1093-0. PMID 12759756.
  37. Boll M, Daniel H, Gasnier B (2004). "The SLC36 family: proton-coupled transporters for the absorption of selected amino acids from extracellular and intracellular proteolysis family". Pflugers Arch. 447 (5): 776–779. doi:10.1007/s00424-003-1073-4. PMID 12748860.
  38. Bartoloni L, Antonarakis SE (2004). "The human sugar-phosphate/phosphate exchanger family SLC37". Pflugers Arch. 447 (5): 780–783. doi:10.1007/s00424-003-1105-0. PMID 12811562.
  39. Mackenzie B, Erickson JD (2004). "Sodium-coupled neutral amino acid (System N/A) transporters of the SLC38 gene family". Pflugers Arch. 447 (5): 784–795. doi:10.1007/s00424-003-1117-9. PMID 12845534.
  40. Eide DJ (2004). "The SLC39 family of metal ion transporters". Pflugers Arch. 447 (5): 796–800. doi:10.1007/s00424-003-1074-3. PMID 12748861.
  41. McKie AT, Barlow DJ (2004). "The SLC40 basolateral iron transporter family (IREG1/ferroportin/MTP1)". Pflugers Arch. 447 (5): 801–806. doi:10.1007/s00424-003-1102-3. PMID 12836025.
  42. Nakhoul NL, Hamm LL (2004). "Non-erythroid Rh glycoproteins: a putative new family of mammalian ammonium transporters". Pflugers Arch. 447 (5): 807–812. doi:10.1007/s00424-003-1142-8. PMID 12920597.

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