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solute carrier family 22 member 1 (organic cation transporter 1, hOCT1, SLC22A1, OCT1)
Function:
- translocates a broad array of organic cations with various structures & molecular weights including
a) model compounds 1-methyl-4-phenylpyridinium (MPP) tetraethylammonium (TEA) N-1-methylnicotinamide (NMN) 4-(4-(dimethylamino)styryl)-N-methylpyridinium (ASP)
b) endogenous compounds choline, guanidine, histamine, epinephrine, adrenaline, noradrenaline & dopamine
c) drugs quinine & metformin
- transport of organic cations is inhibited by a broad array of compounds including: tetramethylammonium (TMA), cocaine, lidocaine, NMDA receptor antagonists, atropine, prazosin, cimetidine, TEA & NMN, guanidine, cimetidine, choline, procainamide, quinine, tetrabutylammonium, & tetrapentylammonium
- translocation of organic cations is electrogenic & pH-independent
- translocates organic cations across the plasma membrane in both directions transports the polyamines spermine & spermidine
- transports pramipexole across the basolateral membrane of the proximal tubular epithelial cells
- choline transport is activated by MMTS
- regulated by intracellular signaling pathways including:
a) inhibition by protein kinase A activation
c) activation by the calmodulin, CAM kinase 2 & LCK
- phosphorylated (putative)
Kinetic parameters:
- KM=1.47 mM for metformin
- KM=229 uM for TEA
- KM=14.6 uM for MPP
- Vmax=396 pmol/min/mg enzyme for metformin uptake
- Vmax=2.89 nmol/min/mg enzyme for TEA uptake
Structure:
- belongs to the major facilitator superfamily, organic cation transporter family
Compartment: basolateral cell membrane
Alternative splicing: named isoforms=4
Expression:
- widely expressed with high level in liver
- isoform 1 & isoform 2 are expressed in liver
- isoforms 1-4 expressed in glial cell lines
- in the liver activated by HNF4A & suppressed by bile acids via NR0B2
- increased by cholesterol treatment in hepatocytes
General
glycoprotein
solute carrier family 22 (SLC22, SLC22A)
transmembrane 12 protein
Properties
SIZE: entity length = 554 aa
MW = 61 kD
COMPARTMENT: cellular membrane
MOTIF: cytoplasmic domain {1-21}
transmembrane domain {22-42}
exoplasmic loop {43-149}
MOTIF: N-glycosylation site {N71}
transmembrane domain {150-170}
cytoplasmic loop {171-176}
transmembrane domain {177-197}
exoplasmic loop {198-206}
transmembrane domain {207-229}
cytoplasmic loop {230-235}
transmembrane domain {236-256}
exoplasmic loop {257-262}
transmembrane domain {263-283}
cytoplasmic loop {284-347}
transmembrane domain {348-368}
exoplasmic loop {369-376}
transmembrane domain {377-397}
cytoplasmic loop {398-402}
transmembrane domain {403-423}
exoplasmic loop {424-431}
transmembrane domain {432-452}
MOTIF: cysteine residue {450}
cytoplasmic loop {453-464}
transmembrane domain {465-485}
exoplasmic loop {486-492}
transmembrane domain {493-513}
cytoplasmic domain {514-554}
Database Correlations
OMIM 602607
UniProt O15245
Pfam PF07690
Kegg hsa:6580
References
UniProt :accession O15245