OHCHR

OCTN2

OCTN2, also known as the Organic Cation/Carnitine Transporter 2, is a protein encoded by the SLC22A5 gene in humans. It is a member of the solute carrier family 22 (SLC22), which is involved in the transport of organic cations, zwitterions, and carnitine across cell membranes. OCTN2 plays a crucial role in the uptake of carnitine, a compound essential for the transport of long-chain fatty acids into the mitochondria for β-oxidation.

Structure

OCTN2 is an integral membrane protein that spans the cell membrane multiple times. It is composed of 557 amino acids and has a molecular weight of approximately 63 kDa. The protein structure includes 12 transmembrane domains, which facilitate its function as a transporter.

Function

OCTN2 is primarily responsible for the high-affinity transport of carnitine into cells. Carnitine is vital for the transport of fatty acids into the mitochondria, where they undergo β-oxidation to produce energy. OCTN2 also transports other organic cations and zwitterions, although carnitine is its primary substrate.

Genetic Mutations and Clinical Significance

Mutations in the SLC22A5 gene can lead to primary carnitine deficiency (PCD), a rare autosomal recessive disorder. PCD is characterized by low levels of carnitine in the blood, leading to symptoms such as muscle weakness, hypoglycemia, and cardiomyopathy. Early diagnosis and treatment with carnitine supplementation can prevent severe complications.

Expression

OCTN2 is expressed in various tissues, including the heart, skeletal muscle, kidney, and placenta. Its expression is regulated by factors such as dietary intake of carnitine and hormonal signals.

Regulation

The activity of OCTN2 is regulated by several mechanisms, including transcriptional control, post-translational modifications, and interaction with other proteins. Hormones such as insulin and glucocorticoids can influence the expression and activity of OCTN2.

Research and Therapeutic Implications

Research on OCTN2 has implications for understanding metabolic disorders, drug interactions, and the development of therapeutic strategies for conditions like primary carnitine deficiency. Understanding the transport mechanisms and regulation of OCTN2 can aid in the development of drugs that target this transporter to modulate carnitine levels in the body.

Also see

• Carnitine
• Primary Carnitine Deficiency
• SLC22A5
• β-oxidation
• Mitochondria