Genes in this family encode components of the circadian rhythms of locomotor activity, metabolism, and behavior.

[9] PER1 and PER2 are necessary for molecular timekeeping and light responsiveness in the master circadian clock in the SCN, but little data is shown on the concrete function for PER3.

[11] The RNA levels of mPer3 oscillate with a circadian rhythm in both the SCN and in the eyes, as well as in peripheral tissues, including the liver, skeletal muscle, and testis.

Functional Per3-/- animals experience only small changes in free-running period,[12] and do not respond significantly differently to light pulses.

[12] Per3 knockout mice experience a slightly shortened period of locomotor activity (by 0.5 hr[13]) and are less sensitive to light, in that they entrain more slowly to changes in the light-dark cycle.

AB047686) is a structural polymorphism due to an insertion or deletion of 18 amino acids in a region encoding a putative phosphorylation domain.

The PER3 protein has been identified to have the following features:[19] The following are some known post transcriptional modifications to the Per3 gene:[19] This article incorporates text from the United States National Library of Medicine, which is in the public domain.