LMPD Database

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LMP006010

UniProt Annotations

Entry Information
Gene Namesolute carrier family 22 (organic cation/zwitterion transporter), member 4
Protein EntryS22A4_HUMAN
UniProt IDQ9H015
SpeciesHuman
Comments
Comment typeDescription
Biophysicochemical PropertiesKinetic 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) {ECO
CautionPubMed: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.
DiseaseRheumatoid arthritis (RA) [MIM
FunctionSodium-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).
InductionOverexpressed upon TNF treatment.
SimilarityBelongs to the major facilitator (TC 2.A.1) superfamily. Organic cation transporter (TC 2.A.1.19) family.
Subcellular LocationMembrane; Multi-pass membrane protein.
SubunitInteracts with PDZK1.
Tissue SpecificityWidely expressed. Highly expressed in whole blood, bone marrow, trachea and fetal liver. Weakly expressed in kidney, skeletal muscle, prostate, lung, pancreas, placenta, heart, uterus, spleen and spinal cord. Highly expressed in intestinal cell types affected by Crohn disease, including epithelial cells. Expressed in CD68 macrophage and CD43 T-cells but not in CD20 B-cells. Predominantly expressed in CD14 cells in peripheral blood mononuclear cells. {ECO