How a protein controls daily production of an enzyme using a special protein-making process

AANAT protein synthesis is influenced by the rhythmic levels of the RNA-binding protein hnRNP R.

• Heterogeneous ribonucleoprotein R (hnRNP R) interacts with the 5' untranslated region of AANAT mRNA.
• hnRNP R contributes to the translation of AANAT through an internal ribosomal entry site.
• Knockdown and overexpression of hnRNP R fine-tunes AANAT protein synthesis.
• AANAT protein levels elevate at night, correlating with increased hnRNP R in the pineal gland.
• Enhanced AANAT production in rat pinealocytes occurs with elevated hnRNP R levels under norepinephrine treatment.

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