Nocturnin (NOCT)

Nocturnin is a phosphatase enzyme encoded by the NOCT gene on human chromosome 4, regulated by the circadian clock, with expression peaking in the early evening[4]. Structurally, it is part of the endonuclease/exonuclease/phosphatase (EEP) family and closely related to CCR4-class deadenylases such as PDE12 and CNOT6L, as well as the DNA repair enzyme TDP2[2][3]. Nocturnin’s previously hypothesized deadenylase activity was not supported by later studies; instead, it acts as an NADP(H) 2′-phosphatase, directly regulating NADP+ and NADPH levels, a function conserved across species[4]. It plays a key role in aligning cellular metabolism to the circadian rhythm and affects metabolic homeostasis—mice lacking Nocturnin are resistant to diet-induced obesity, and genetic variation in humans has been linked to cancer risk and body mass regulation[4][5]. No direct pharmacological drugs or inhibitors are reported as of yet. Nocturnin localizes to the mitochondria and cytoplasm[4], modulating metabolic enzymes in a time-of-day dependent manner. Key structural features include a globular α/β sandwich fold, a magnesium ion in the catalytic center, and unique surface and active site properties distinct from other CCR4-like deadenylases, contributing to its substrate specificity[2][3][1]. If further details or more precise molecular or pharmacological information become known or are required for broad drug databases, consult recent literature as Nocturnin’s enzymatic function has only recently been clarified.

Other names

CCRN4LCCR4Carbon catabolite repression 4-like proteinCCR4LCcr4cNOCcircadian deadenylase NOCCCR4 protein homologCCR4-like (carbon catabolite repression 4, S. cerevisiae)curled (Drosophila)