carnitine transmembrane transport
Definition
Target type: biologicalprocess
The directed movement of carnitine across a membrane. [GO_REF:0000069, GOC:pr, GOC:TermGenie]
Carnitine transmembrane transport is a crucial process for the metabolism of fatty acids. It involves the movement of carnitine, a small organic molecule, across the mitochondrial membrane, specifically the inner mitochondrial membrane. This transport is essential for the entry of long-chain fatty acids into the mitochondria, where they can be broken down for energy production via beta-oxidation. The process is facilitated by a family of transmembrane proteins known as carnitine acyltransferases (CATs). There are three major CATs: CAT1, CAT2, and CPT1.
CAT1 is primarily responsible for the uptake of carnitine into the cytoplasm from the blood. CAT2 is located on the inner mitochondrial membrane and facilitates the transfer of carnitine from the cytoplasm into the mitochondrial matrix. CPT1, also located on the inner mitochondrial membrane, is responsible for the formation of acylcarnitine, a derivative of carnitine that is able to cross the mitochondrial membrane.
The carnitine shuttle begins when a long-chain fatty acid is activated by attaching to CoA to form acyl-CoA. Acyl-CoA cannot directly cross the mitochondrial membrane. Therefore, CPT1 catalyzes the transfer of the acyl group from CoA to carnitine, forming acylcarnitine. Acylcarnitine can then cross the mitochondrial membrane via the carnitine/acylcarnitine translocase (CACT), which is a transporter protein that exchanges acylcarnitine for carnitine.
Once inside the mitochondrial matrix, CAT2 transfers the acyl group back to CoA, regenerating acyl-CoA. This acyl-CoA can now enter the beta-oxidation pathway, where it is broken down into acetyl-CoA, which can be used for energy production. Carnitine is then transported back out of the mitochondrial matrix by CACT, completing the carnitine shuttle.
The carnitine shuttle plays a critical role in energy metabolism. It allows the body to use long-chain fatty acids as a source of energy, particularly during periods of fasting or exercise when glucose levels are low. Disorders affecting the carnitine shuttle can lead to various metabolic problems, such as muscle weakness, hypoglycemia, and cardiomyopathy.'
"
Proteins (4)
| Protein | Definition | Taxonomy |
|---|---|---|
| Solute carrier family 22 member 5 | An organic cation/carnitine transporter 2 that is encoded in the genome of human. [PRO:DNx, UniProtKB:O76082] | Homo sapiens (human) |
| Solute carrier family 22 member 4 | A solute carrier family 22 member 4 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q9H015] | Homo sapiens (human) |
| Solute carrier family 22 member 16 | A solute carrier family 22 member 16 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q86VW1] | Homo sapiens (human) |
| Solute carrier family 22 member 5 | An organic cation/carnitine transporter 2 that is encoded in the genome of human. [PRO:DNx, UniProtKB:O76082] | Homo sapiens (human) |
Compounds (6)
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| carnitine | amino-acid betaine | human metabolite; mouse metabolite | |
| tetraethylammonium | Tetraethylammonium: A potassium-selective ion channel blocker. (From J Gen Phys 1994;104(1):173-90) | quaternary ammonium ion | |
| cephaloridine | cefaloridine : A cephalosporin compound having pyridinium-1-ylmethyl and 2-thienylacetamido side-groups. A first-generation semisynthetic derivative of cephalosporin C. Cephaloridine: A cephalosporin antibiotic. | beta-lactam antibiotic allergen; cephalosporin; semisynthetic derivative | antibacterial drug |
| ergothioneine | ergothioneine thione form : A L-histidine derivative that is N(alpha),N(alpha),N(alpha)-trimethyl-L-histidine in which the hydrogen at position 2 on the imdazole ring is replaced by a thioxo group. | 1,3-dihydroimidazole-2-thiones; amino-acid betaine; L-histidine derivative; sulfur-containing amino acid | antioxidant; chelator; fungal metabolite; plant metabolite; xenobiotic metabolite |
| cefepime | cefepime : A cephalosporin bearing (1-methylpyrrolidinium-1-yl)methyl and (2Z)-2-(2-amino-1,3-thiazol-4-yl)-2-(methoxyimino)acetamido groups at positions 3 and 7, respectively, of the cephem skeleton. Cefepime: A fourth-generation cephalosporin antibacterial agent that is used in the treatment of infections, including those of the abdomen, urinary tract, respiratory tract, and skin. It is effective against PSEUDOMONAS AERUGINOSA and may also be used in the empiric treatment of FEBRILE NEUTROPENIA. | cephalosporin; oxime O-ether | antibacterial drug |
| acetylcarnitine | O-acetyl-L-carnitine : An O-acyl-L-carnitine where the acyl group specified is acetyl. It facilitates movement of acetyl-CoA into the matrices of mammalian mitochondria during the oxidation of fatty acids. | O-acetylcarnitine; saturated fatty acyl-L-carnitine | human metabolite; Saccharomyces cerevisiae metabolite |