SLC3A2 - 4F2 cell-surface antigen heavy chain - human protein (Function)
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SLC3A2 »  4F2 cell-surface antigen heavy chain  (4F2hc)
Protein also known as:  Lymphocyte activation antigen 4F2 large subunit; CD antigen CD98.
Gene name:  SLC3A2
Family name: SLC3A transporter
Entry whose protein(s) existence is based on evidence at protein level
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Required for the function of light chain amino-acid transporters. Involved in sodium-independent, high-affinity transport of large neutral amino acids such as phenylalanine, tyrosine, leucine, arginine and tryptophan. Involved in guiding and targeting of LAT1 and LAT2 to the plasma membrane. When associated with SLC7A6 or SLC7A7 acts as an arginine/glutamine exchanger, following an antiport mechanism for amino acid transport, influencing arginine release in exchange for extracellular amino acids. Plays a role in nitric oxide synthesis in human umbilical vein endothelial cells (HUVECs) via transport of L-arginine. Required for normal and neoplastic cell growth. When associated with SLC7A5/LAT1, is also involved in the transport of L-DOPA across the blood-brain barrier, and that of thyroid hormones triiodothyronine (T3) and thyroxine (T4) across the cell membrane in tissues such as placenta. Involved in the uptake of methylmercury (MeHg) when administered as the L-cysteine or D,L-homocysteine complexes, and hence plays a role in metal ion homeostasis and toxicity. When associated with SLC7A5 or SLC7A8, involved in the cellular activity of small molecular weight nitrosothiols, via the stereoselective transport of L-nitrosocysteine (L-CNSO) across the transmembrane. Together with ICAM1, regulates the transport activity LAT2 in polarized intestinal cells, by generating and delivering intracellular signals. When associated with SLC7A5, plays an important role in transporting L-leucine from the circulating blood to the retina across the inner blood-retinal barrier.  
  • CuratedUniProtKB
According to TCDB this is a transporter from family:
the rbat transport accessory protein (rbat) family  8.A.9.2.2  
GO molecular function 
Calcium:sodium antiporter activitydefinition[GO:0005432]  
  • TASUniProtKB
Catalytic activitydefinition[GO:0003824] silver  
  • IEAInterPro 2 GO
Cation bindingdefinition[GO:0043169] silver  
  • IEAInterPro 2 GO
Double-stranded RNA bindingdefinition[GO:0003725]  
Neutral amino acid transmembrane transporter activitydefinition[GO:0015175]  
  • ISSOrtholog Curator
Poly(A) RNA bindingdefinition[GO:0044822]  
  • IDAUniProtKB
Protein bindingdefinition[GO:0005515]  
  • IPIUniProtKB
GO biological process 
Amino acid transportdefinition[GO:0006865]  
  • TASUniProtKB
Calcium ion transportdefinition[GO:0006816]  
  • NASUniProtKB
Carbohydrate metabolic processdefinition[GO:0005975] silver  
  • IEAInterPro 2 GO
Cell growthdefinition[GO:0016049]  
  • NASUniProtKB
Leucine importdefinition[GO:0060356]  
  • ISSOrtholog Curator
Response to exogenous dsRNAdefinition[GO:0043330]  
Sodium ion transmembrane transportdefinition[GO:0035725]  
Tryptophan transportdefinition[GO:0015827]  
  • ISSOrtholog Curator
Enzymatic activity 
According to CAZy, this protein is belongs to the following pathway:
Glycoside Hydrolase Family 13  GH13  
According to KEGG, this protein belongs to the following pathway:
Protein digestion and absorption  hsa04974+6520  
According to Reactome, this protein belongs to the following pathways:
Amino acid transport across the plasma membrane  REACT_13796  
Basigin interactions  REACT_12560  
More information is available from:
Arginine uptake is inhibited by increasing concentrations of leucine in the presence of Na(+).  
  • CuratedUniProtKB

Biophysicochemical properties

Kinetic parameters
KM 120 uM for arginine (in the presence of NaCl)
KM 236 uM for leucine (in the presence of NaCl)
KM 138 uM for arginine (in the absence of NaCl)
KM 295 uM for glutamine (in the presence of NaCl)


Biological process 
Amino-acid transport  definition   [KW-0029]
Transport  definition   [KW-0813]
Technical term 
Reference proteome  definition   [KW-1185]

Further external links

Enzyme and pathway databases
SABIO-RK: P08195
GeneWiki: SLC3A2
GenomeRNAi: 6520
PRO: PR:P08195