Block in Nuclear Localization of <i>period</i> Protein by a Second Clock Mutation, <i>timeless</i>

TLDR

In wild‑type Drosophila, the period protein (PER) localizes to nuclei in eyes and brain and oscillates with a circadian rhythm, while the timeless (tim) gene may regulate PER abundance and nuclear localization. The tim mutation blocks PER nuclear localization; PER proteins lacking the PAS domain and flanking sequences remain nuclear in tim mutants, indicating a PER segment normally inhibits nuclear entry in these mutants.

Abstract

In wild-type Drosophila , the period protein (PER) is found in nuclei of the eyes and brain, and PER immunoreactivity oscillates with a circadian rhythm. The studies described here indicate that the nuclear localization of PER is blocked by timeless ( tim ), a second chromosome mutation that, like per null mutations, abolishes circadian rhythms. PER fusion proteins without a conserved domain (PAS) and some flanking sequences are nuclear in tim mutants. This suggests that a segment of PER inhibits nuclear localization in tim mutants. The tim gene may have a role in establishing rhythms of PER abundance and nuclear localization in wild-type flies.