Phospho protein % in the cell - signal transduction (Jun/06/2007 )

Dear members,
i m curious to know the cell signaling process, on the way i have couple of questions kept me busy. could you help me to understand the following questions
1- what is the approximate percentage of phospho proteins in side the cell (despite the cell type) during normal cell growth?
2- is there any steep phosphorylation net increase or decrease upon stimulation?
3- is there any balance exist between phosphorylation and dephosphorylation events ?

thanks in advance
sravan

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these questions are too general to answer precisely;
Q1: "normality" of growth depends on type of cell; adequate stimulations often increase total phosphorylation; ca. 1% of phosphorylations are tyrosinyl phosphorylations
Q2: ?
Q3: phosphorylations for individual signaling molecules are transient as dephosphorylation works in parallel or proteolytic degradation; cis- and transphorylations are regulated by trans-dephosphorylations; so kinetics of phosphorylation in a cell are the result of cis-/transphosphorylations and trans-dephosphorylation

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