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Biochem Quiz 8
Terms in this set (21)
What do protein kinases do?
catalyze phosphorylation reactions
What is the most common donor of phosphoryl groups?
What is a phosphoryl group?
Which phosphoryl group on ATP gets donated to a specific AA of the acceptor protein ?
terminal gamma phosphoryl group
In eukaryotes, the acceptor residue commonly contained a ____ group in its side chain.
Which three resides are examples of this?
serine, threonine, and tyrosine
The acceptors in protein-phosphorylatin are located where? Why?
inside cells, because ATP is abundant there
Protein kinases vary in their degree of _____
What kind of kinases phosphorylate one type of protein, or sever closely related ones?
dedicated protein kinases
What kind of kinases phosphorylate many targets by recognizing related sequences, therefore coordinating diverse processes?
multifunctional protein kinases
PKA recognizes what kind of sequence?
At which residues does PKA phosphorylate?
Serine or Threonine
What is the primary determinant of the specificity PKA?
the AA sequence surrounding the Ser or Thr site
What do protein phosphatases do? How?
they catalyze the removal of phosphoryl groups attached to proteins by hydrolyzing the bond
Which step in phosphorylation or dephosphorylation has the highest free E (G)?
when the protein has not yet been phosphorylated
Which step in phosphorylation or dephosphorylation has the lowest free E (G)?
when the protein has been dephosphorylated, yieldeing Protein-OH + HOPO3(2-)
When the unmodified hydroxyl-containing side chain is regenerated through dephosphorylation, what is produced?
What is a highly conserved phosphatase that suppresses cancer-promoting activity?
(T/F) Phosphorylation and dephosphorylation reactions are the reverse of each other?
What is the rate of phosphorylation and dephosphorylation reactions in the absence of enzymes?
so small it's negligible
Target proteins cycle ____ between unphosphorylated and phosphorylated forms
What does the rate of cycling between nphosphorylated and phosphorylated forms depend on?
relative activity of kinases and phosphatases
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