SLC22A4 - Solute carrier family 22 member 4 - human protein (Function)
 
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Protein
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References

 
SLC22A4 »  Solute carrier family 22 member 4
 
Protein also known as:  Organic cation/carnitine transporter 1.
Gene name:  SLC22A4
Entry whose protein(s) existence is based on evidence at protein level
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GENE REF ISO

Function

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Overview 
Sodium-ion dependent, low affinity carnitine transporter. Probably transports one sodium ion with one molecule of carnitine. Also transports organic cations such as tetraethylammonium (TEA) without the involvement of sodium. Relative uptake activity ratio of carnitine to TEA is 1.78. A key substrate of this transporter seems to be ergothioneine (ET).  
3
  • UniProtKB
According to TCDB this is a transporter from familys:
the major facilitator superfamily (mfs)  2.A.1.19.2  
the major facilitator superfamily (mfs)  2.A.1.19.26  
GO molecular function 
ATP bindingdefinition[GO:0005524]  
1
  • UniProtKB KW
Carnitine transmembrane transporter activitydefinition[GO:0015226]  
1
  • MGI
Cation:cation antiporter activitydefinition[GO:0015491]  
1
  • BHF-UCL
Nucleotide bindingdefinition[GO:0000166]  
1
  • PINC
PDZ domain bindingdefinition[GO:0030165]  
1
  • BHF-UCL
Protein bindingdefinition[GO:0005515]  
1
  • BHF-UCL
Quaternary ammonium group transmembrane transporter activitydefinition[GO:0015651]  
1
  • BHF-UCL
Secondary active organic cation transmembrane transporter activitydefinition[GO:0008513]  
1
  • PINC
Symporter activitydefinition[GO:0015293]  
1
  • UniProtKB KW
GO biological process 
Body fluid secretiondefinition[GO:0007589]  
1
  • PINC
Carnitine metabolic processdefinition[GO:0009437] silver  
1
  • Ortholog Compara
Carnitine transmembrane transportdefinition[GO:1902603]  
2
  • GOC
  • Ortholog Compara
Carnitine transportdefinition[GO:0015879]  
1
  • MGI
Cation transmembrane transportdefinition[GO:0098655]  
1
  • GOC
Organic cation transportdefinition[GO:0015695]  
1
  • PINC
Quaternary ammonium group transportdefinition[GO:0015697]  
1
  • BHF-UCL
Sodium ion transportdefinition[GO:0006814]  
1
  • UniProtKB KW
Triglyceride metabolic processdefinition[GO:0006641] silver  
1
  • Ortholog Compara
Pathways 
According to Reactome, this protein belongs to the following pathway:
Organic cation transport  REACT_22357  
Caution 
PubMed:9426230 reported that this protein does not transport carnitine, however, experiments were done with the Phe-503 variant, which affects the ability to transport carnitine. PubMed:15459889 showed that, although weakly, it can also transport carnitine at some level. Its function in carnitine transport is therefore unclear.  
1
  • UniProtKB
 

Biophysicochemical properties

Kinetic parameters
KM 0.470 mM for TEA (at 37 degrees Celsius and pH 7.4)
Vmax 0.974 nmol/min/mg enzyme toward TEA (at 37 degrees Celsius and pH 7.4)
Dependence
pH More active at neutral and alkaline pHs than at acidic pHs.

Keywords

Biological process 
Ion transport  definition   [KW-0406]
Sodium transport  definition   [KW-0739]
Symport  definition   [KW-0769]
Transport  definition   [KW-0813]
Technical term 
Reference proteome  definition   [KW-1185]
 

Further external links

GeneWiki: SLC22A4
GenomeRNAi: 6583
PRO: PR:Q9H015