Selenoprotein P (SELENOP)

Function

Selenoprotein P is a selenium-transporting peptide hormone involved in antioxidant defense, selenium distribution, oxidative stress regulation, endothelial protection, and metabolic communication. SELENOP functions as the primary transport protein responsible for delivering selenium from the liver to peripheral tissues requiring selenium-dependent antioxidant enzyme activity.

The hormone contributes to maintenance of glutathione peroxidase activity, redox balance, mitochondrial protection, and cellular defense against oxidative stress. Selenoprotein P also participates in endothelial signaling, immune adaptation, and communication between hepatic metabolism and peripheral tissue antioxidant requirements. Through these actions, it helps coordinate systemic selenium homeostasis and oxidative protection.

Production

Selenoprotein P is produced mainly by the liver, although additional synthesis occurs in endothelial cells, brain tissue, kidneys, and additional metabolic organs. The protein contains multiple selenium-containing selenocysteine residues that enable selenium transport and antioxidant-associated functions.

After synthesis, SELENOP is secreted into circulation where it transports selenium to tissues including brain, testes, kidneys, and immune structures. Hepatic production therefore serves as a major endocrine mechanism controlling whole-body selenium distribution.

Regulation

Selenoprotein P production is regulated by selenium availability, oxidative stress pathways, inflammatory signaling, hepatic metabolic status, insulin signaling, and nutritional selenium intake. Low selenium status can alter synthesis dynamics and peripheral tissue distribution.

SELENOP acts through receptor-mediated uptake pathways involving apolipoprotein receptors and tissue-specific selenium transport systems. Cellular uptake supports synthesis of selenium-dependent antioxidant enzymes involved in redox regulation and mitochondrial protection. Inflammatory signaling and metabolic stress can influence both circulating concentrations and tissue responsiveness. Through these integrated nutrient-signaling systems, selenoprotein P coordinates selenium transport, antioxidant defense, endothelial protection, and oxidative stress adaptation.