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CMB2002 Lecture 4

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Outline the basics of intercellular Ca2+ waves
- IP3R undergoes CICR
- IP3 and Ca2+ then move through the gap junctions between cells
> These can be between different cell types
Using Glycogen breakdown in the liver how are Ca2+ signals decoded into a physiological response?
Increase in Glucagon = increase in Ca2+ spikes.

1) Ca2+ binds effector protein (Ca.Cam)
2) Response element activated (Ca.Cam Kinase II)
3) This phosphorylates substrate protein and activates then enzyme (Phosphorylase Kinases-P)
4) This then phosphorylates its substrate protein (Phosphorylase)
5) Which then breaks down glycogen to glucose and releases it into the blood.
How does an increase in Ca.CamKII activity correlate to the frequency of Ca2+ spike frequency?
- Different frequencies of Ca2+ spike = different levels of enzyme activity
- At low Ca2+ spike frequencies the enzyme has enough time to return to its resting state therefore less time is spent in its active state.
- During periods of high Ca2+ spike frequency the enzyme doesn't have time to relax and so more time is spent in its active state.