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MCB
572
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Homework and Readings for 09/11/2008 Students will present the following two papers on ultrasensitivity in the MAP kinase cascades. Homework: The general outline of the homework is to write a BRIEF summary of the paper that you read. Please include in your summary a disucssion of the following issues: (kindly provided by your student discussion leaders to help in your understanding of the papers. PNAS paper: In your summary of this paper discuss the role and/or significance of the following: (i) THREE MAP kinases in the cascade (ii) phosphatases (iii) number of phosphorylation events at each step Science paper: In your summary of this paper discuss the role and/or significance of the use of Xenopus embryos. In additon, discuss BRIEFLY two factors that contribute to the ultrasensitivity of the MAP kinase cascade. SUPPLEMENTARY, YET ESSENTIAL STUFF: YES! ultrasensitivity make complete sense. The 2 papers below are relevant. Take a look at the first one..the TIBS review. The second one has some nice data that confirms the "two hit" hypothesis for how MAPkinase activate each other. The presenters are going to draw from these two papers, to tie it all together. You might want to look at them too. 1. Ferrell TIBS 460, 1996. A discussion of the underlying mechanisms of ultrasensitivity, using rather nice graphical representations of enzyme kinetics. I will try and make this transparent in class as well. 2. Ferrell and Bhatt. JBC 272, 19008. 1997 Really nice study showing that phosphorylation proceeds by a distributive mechanism (2 hits) as the model of ultrasensitivity requires.
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