Dr' Stuart Reichler

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• Dr. Stuart Reichler
• Lectures posted on class website
• No class W 11/22

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Signal transduction step by step Response
such as changes in cellular components or
production of new cellular components
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Transduction can involve activation or
inactivation of proteins.
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Cellular responses may involve changes in the
expression of genes.
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Why so many steps?
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Multiple steps allow for signal amplification
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Multiple steps allow for signal specificity.
Different relay molecules lead to different
responses
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Calcium is a common effector. Cytoplasmic
calcium levels are normally low.
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During signal transduction, calcium can be
released into the cytoplasm Perception
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During signal transduction, calcium can be
released into the cytoplasm Transduction
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During signal transduction, calcium can be
released into the cytoplasm Response
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During signal transduction, calcium can be
released into the cytoplasm
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General model of Ca signaling
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General model of Ca signaling
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Plant Responses involving changes in cytoplasmic
Ca
Tbl 1. Scrase-Field and Knight, Current Opinion
in Plant Biology 2003, 6500506
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How can calcium be involved in so many different
responses? How can changes in calcium give rise
to specificity?
Tbl 1. Scrase-Field and Knight, Current Opinion
in Plant Biology 2003, 6500506
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2 hypotheses about how Ca signals are
transduced Signatures vs. Switches
Fig 1. Scrase-Field and Knight, Current Opinion
in Plant Biology 2003, 6500506
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Photosynthesis Plants can make sugar using
energy from the sun, water from the ground, and
CO2 from the air.
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Stomata regulate gas exchange CO2 in, O2 and
water out
H2O
H2O
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Stomata
closed
open
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Opening and closing of stomata
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Ca fluxes in guard cells in response to hormone
or stress that cause stomatal closing. Wildtype
vs. det3 and gca2 mutants that fail to close
stomata following treatment
Fig 5. Sanders et al., The Plant Cell, S401S417,
Supplement 2002
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Stomata aperture in response to Ca spikes More
spikes more closing
Fig 1. Allen et al., Nature, Vol 4111053-1057,
28 June 2001
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Spike timing is critical for response
Fig 2. Allen et al., Nature, Vol 4111053-1057,
28 June 2001
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Duration of spikes for stomata closing
Fig 2. Allen et al., Nature, Vol 4111053-1057,
28 June 2001
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2 hypotheses about how Ca signals are
transduced Signatures vs. Switches
Fig 1. Scrase-Field and Knight, Current Opinion
in Plant Biology 2003, 6500506
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• Dr. Stuart Reichler
• Lectures posted on class website
• No class W 11/22