Table 2.

Different transport systems of amino acids.

Transport system [182, 560, 561]	Meaning	Transporters from SLC families
System A	Proteins cotransport Na+ with small, polar amino acids amino acids	SLC38
System N	Proteins cotransport Na+ with His, Gln, or Asn and the simultaneous antiport of protons	SLC38
System L	Proteins that have Na+ independent transport of large hydrophobic neutral amino acids	SLC3/7, SLC43
System ASC	Proteins cotransport Na+ with Ala, Ser, or Cys	SLC1
System asc	Proteins transport small neutral amino acids	SLC3/7
System xC −	Proteins exchange Cys for Glu	SLC3/7
System xAG −	Proteins cotransport Na+ with Asp or Glu and antiport K+	SLC1
System y+L	Proteins cotransport Na+ with cationic and neutral amino acids	SLC3/7
System y+	Proteins transport cationic amino acids	SLC7
System b0,+	Proteins transport cationic amino acids as well as neutral amino acids	SLC3/7
System B0	Proteins cotransport Na+ with neutral amino acids	SLC6