Movement between the nucleus and cytoplasm and mCRY's role in blocking mPER2 protein breakdown in the biological clock

mPER2 shuttles between the nucleus and cytoplasm, influenced by mCRY proteins.

• The core mechanism for circadian rhythms involves feedback loops where clock gene products inhibit their own expression.
• Nuclear accumulation of mPER2 occurs approximately 6 hours after mRNA expression peaks, and this process is facilitated by mCRY proteins.
• mPER2 is prevented from degradation by the proteasome when retained in the nucleus by mCRY proteins.
• Conversely, mPER2 can prevent the degradation of mCRY proteins, suggesting a reciprocal regulatory relationship.
• The findings support a model where mPER2 is targeted for degradation unless stabilized by its interaction with mCRY proteins.

Simplified