Table 1 Amino acid transporters, their properties and involvement in diseases

Substrates are given in one-letter code. Cit, citrulline; Cn, cystine; O, ornithine. The ‘Function’ column includes references to amino acid transport systems. These systems have acronyms indicating the substrate specificity of the transporter. Upper-case letters indicate Na+-dependent transporters (with the exception of system L, system T and the proton amino acid transporters); lower case is used for Na+-independent transporters (for example asc, y+ and xc). X or x indicate transporters for anionic amino acids (as in XAG and xc). The subscript AG indicates that the transporter accepts aspartate and glutamate, and the subscript c indicates that the transporter also accepts cystine. Y+ or y+ refer to transporters for cationic amino acids (an Na+-dependent cationic amino acid transporter has not been unambiguously defined and as a result Y+ is not used), B or b refers to amino acid transporters of broad specificity with superscript 0 indicating a transporter accepting neutral amino acids and superscript + indicating a transporter for cationic amino acids. T stands for a transporter for aromatic amino acids, and system N indicates selectivity for amino acids with nitrogen atoms in the side chain. In the remaining cases, the preferred substrate is indicated by the one-letter code for amino acids. For example, system L refers to a leucine-preferring transporter and system ASC to a transporter preferring alanine, serine and cysteine. Proline and hydroxyproline are referred to as imino acids. Owing to historic idiosyncrasies, the nomenclature for plasma-membrane amino acid transport systems is not completely consistent, but is widely used in the field. AAT amino acid transporter.

SLCAcronymSubstrate(s)FunctionDisease/phenotype
SLC1A1EAAT3D,E,CnSystem XAGDicarboxylic aminoaciduria, OCD
SLC1A2EAAT2D,ESystem XAG
SLC1A3EAAT1D,ESystem XAGEpisodic ataxia?
SLC1A4ASCT1A,S,CSystem ASC
SLC1A5ASCT2A,S,C,T,QSystem ASCTumour growth
SLC1A6EAAT4D,ESystem XAG
SLC1A7EAAT5D,ESystem XAG
SLC3A1rBATTrafficking subunitsHeavy chains of heteromeric AATCystinuria
SLC3A24F2hcTrafficking subunitsHeavy chains of heteromeric AATTumour growth
SLC6A5GlyT2GSystem GlyHyperekplexia
SLC6A7PROTPProline transporter
SLC6A9GlyT1GSystem Gly
SLC6A14ATB0,+All neutral and cationic amino acidsSystem B0,+Obesity?
SLC6A15B0AT2P,L,V,I,MSystem B0
SLC6A17NTT4/B0AT3L,M,P,C,A,Q,S,H,GSystem B0
SLC6A18XT2/B0AT3G, ASystem GlyHyperglycinuria? Hypertension?
SLC6A19B0AT1All neutral amino acidsSystem B0Hartnup disorder, hypertension?
SLC6A20IMINOPSystem IMINOIminoglycinuria
SLC7A1CAT-1K,R,OSystem y+
SLC7A2CAT-2K,R,OSystem y+
SLC7A3CAT-3K,R,OSystem y+
SLC7A5LAT1/4F2hcH,M,L,I,V,F,Y,WSystem LTumour growth
SLC7A6y+LAT2/4F2hcK,R,Q,H,M,LSystem y+L
SLC7A7y+LAT1/4F2hcK,R,Q,H,M,L,A,CSystem y+LLysinuric protein intolerance
SLC7A8LAT2/4F2hcAll neutral amino acids, except PSystem L
SLC7A9b0,+AT/rBATR,K,O,CnSystem b0,+Cystinuria
SLC7A10Asc-1/4F2hcG,A,S,C,TSystem asc
SLC7A11xCT/4F2hcD,E,CnSytem xc
SLC7A12Asc-2G,A,S,C,TSystem asc
SLC7A13AGT1D,EAsp, Glu transporter
SLC16A10TAT1W,Y,FSystem TBlue diaper syndrome?
SLC17A6VGLUT2EVesicular Glu transporter
SLC17A7VGLUT1EVesicular Glu transporter
SLC17A8VGLUT3EVesicular Glu transporterNon-syndromic deafness
SLC25A2ORC2K,R,H,O,CitOrn/Cit carrier
SLC25A12AGC1D,EAsp/Glu carrierGlobal cerebral hypomyelination
SLC25A13AGC2D,EAsp/Glu carrierType II citrullinaemia, neonatal intrahepatic cholestasis
SLC25A15ORC1K,R,H,O,CitOrn/Cit carrierHHH syndrome
SLC25A18GC2EGlu carrier
SLC25A22GC1EGlu carrierNeonatal myoclonic epilepsy
SLC32A1VIAATG,GABAVesicular Gly/GABA transporter
SLC36A1PAT1G,P,AProton AATHair colour (horses)
SLC36A2PAT2G,P,AProton AATIminoglycinuria
SLC36A4PAT4P,WAmino acid sensor
SLC38A1SNAT1G,A,N,C,Q, H,MSystem A
SLC38A2SNAT2G,P,A,S,C,Q,N,H,MSystem A
SLC38A3SNAT3Q,N,HSystem N
SLC38A4SNAT4G,A,S,C,Q,N,MSystem A
SLC38A5SNAT5Q,N,H,ASystem N
SLC43A1LAT3L,I,M,F,VSystem L
SLC43A2LAT4L,I,M,F,VSystem L
Not assignedCystinosinCnLysosomal Cys transporterCystinosis