PSY397H1 Lecture Notes - Lecture 8: Circadian Clock, Kaic, Cryptochrome
Document Summary
Ordered kaic autokinase and autophosphatase activities drive the circadian oscillator. Kai c is also a transcription factor that drives the kai cluster in the genome. The period can be anywhere from 16 to 24h, thus not a very accurate clock. However, the concentration of kai proteins are heavily regulated in nature and therefore likely have a much stricter clock than in lab. Light creates atp which leads to quicker phosphorylations of kai c that drives a quicker cycle: more adp slows down phosphorylation of kai. Dark produces phase shifts by inhibition phosphorylation step. Certain mechanisms are conserved all over phylogeny: cryptochrome: is to transduce blue light into an energetic form that is essential to the cell, photolyases: repair light caused dna damage, other affect circadian clocks. Cryptochrome functions: mammals: direct role in rhythm production, plants: blue light photoreception, inhibition of stem elongation, photoperiodism, light-induced changes in gene expression.