Period (gene) - Mammalian Homologs of per

Mammalian Homologs of per

In mammals, there are three known PER family genes: PER1, PER2, and PER3. The mammalian molecular clock has homologs to the proteins found in Drosophila. A homolog of CLOCK plays the same role in the human clock, and CYC is replaced by BMAL1. CRY has two human homologs, CRY1 and CRY2. A computational model for model has been developed by Jean-Christophe Leloup and Adam Goldbeter to simulate the feedback loop created by the interactions between these proteins and genes, including the per gene and PER protein.

The human homologs show sequence and amino acid similarity to Drosophila Per and also contain the PAS domain and nuclear localization sequences that the Drosophila Per have. The human proteins are expressed rhythmically in the suprachiasmatic nucleus as well as areas outside the SCN. Additionally, while Drosophila PER moves between the cytoplasm and the nucleus, mammalian PER is more compartmentalized: mPer1 primarily localizes to the nucleus and mPer2 to the cytoplasm.