(R)-carnitine transport

Definition

Target type: biologicalprocess

The directed movement of a (R)-carnitine into, out of or within a cell, or between cells, by means of some agent such as a transporter or pore. [GOC:TermGenie, PMID:16365044, PMID:20357772, PMID:20829798]

**(R)-Carnitine Transport**

**(R)-Carnitine** is a quaternary ammonium compound essential for the transport of long-chain fatty acids into the mitochondria for beta-oxidation, the primary energy-producing pathway for these molecules. This process is critical for energy generation, particularly during periods of fasting or intense physical activity.

**(1) Cellular Uptake:**

* **Carnitine uptake** occurs primarily in the small intestine, where it is absorbed from the diet or supplemented forms.
* It also enters cells through a **sodium-dependent carnitine transporter** (OCTN2) found on the plasma membrane of many tissues.
* **OCTN2** is a multispecific transporter that also handles other compounds like choline and butyrate.
* Once inside the cell, (R)-carnitine can be further transported into the mitochondria.

**(2) Mitochondrial Transport:**

* The **mitochondrial membrane** is impermeable to long-chain fatty acids.
* **Carnitine acyltransferases** (CATs) play a key role in shuttling fatty acids across this membrane.
* **CAT1** is located on the outer mitochondrial membrane and catalyzes the formation of **acylcarnitine** from fatty acyl-CoA and carnitine.
* **Acylcarnitine** is then transported into the mitochondrial matrix by the **carnitine/acylcarnitine translocase** (CACT), which is located on the inner mitochondrial membrane.
* Once inside the matrix, **CAT2** hydrolyzes acylcarnitine, releasing free carnitine and fatty acyl-CoA, which can then enter beta-oxidation.

**(3) Regulation and Importance:**

* The transport of (R)-carnitine is tightly regulated by the availability of carnitine, the concentration of fatty acids, and the energy demands of the cell.
* **Deficiency** in carnitine can lead to impaired fatty acid oxidation and energy production, with consequences for muscle function, energy levels, and overall metabolism.
* **Genetic disorders** affecting the expression or function of OCTN2, CATs, or CACT can also disrupt carnitine transport and lead to various metabolic problems.

**Summary:**

(R)-carnitine transport is a crucial process for energy production by facilitating the entry of long-chain fatty acids into mitochondria for beta-oxidation. This process involves cellular uptake, mitochondrial transport, and regulation by specific transporters and enzymes. Maintaining adequate carnitine levels is important for optimal energy metabolism and overall health.'
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Proteins (1)

Compounds (4)