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From the options below, identify the process with which each of the phosphorylation processes listed is most closely associated.
A Activation of nuclear export
B Breakdown of the nuclear envelope at the prometaphase stage of mitosis
C Direct activation of a transcription factor
D Gluconeogenesis: the synthesis of glucose from pyruvate and other non-carbohydrate molecules
E Glycogenesis: the synthesis of glycogen
F Glycolysis: the breakdown of glucose to yield pyruvate
G Recruitment to the plasma membrane of proteins with PH domains, including protein kinase B
H Reduction of the likelihood that a cell will initiate apoptosis
I Increase of the likelihood that a cell will initiate apoptosis
J Release of calcium from the endoplasmic reticulum
K Synthesis of collagen
L Targeting proteins to the lysosome
M The Krebs cycle
1. Phosphorylation and decarboxylation of oxaloacetate to yield phosphoenolpyruvate.
Your Answer:
Answer: D, Gluconeogenesis: the synthesis of glucose from pyruvate and other non-carbohydrate molecules.
This reaction bypasses an irreversible step in the glycolytic pathway. From phosphoenolpyruvate, all the steps of glycolysis are
reversible until fructose 1,6 bisphosphate. See figure 13.9 on book page 217.
2. Phosphorylation of fructose-6-phosphate to yield fructose 1,6 bisphosphate.
Your Answer:
Answer: F, Glycolysis: the breakdown of glucose to yield pyruvate. This step commits the sugar to be broken down to pyruvate.
See book pages and 209 and 224.
3. Phosphorylation of bcl-2 by p38.
Your Answer:
Answer: I, increase of the likelihood that a cell will initiate apoptosis. bcl-2 can associate with BAX,
preventing BAX from dimerizing and forming channels through which cytochrome c can leave mitochondria. Phosphorylated bcl-2 can no
longer associate with BAX, leaving the BAX free to release cytochrome c and therefore initiate apoptosis. See book page 311.
4.Phosphorylation of the bcl-2 family member BAX by protein kinase B.
Your Answer:
Answer: H, reduction of the likelihood that a cell will initiate apoptosis. Phosphorylated BAX
is unable to dimerize and form channels through which cytochrome c can leave mitochondria. Phosphorylation of BAX therefore
inhibits apoptosis. See book page 309.
5. Phosphorylation of mannose residues to yield mannose-6-phosphate residues.
Your Answer:
Answer: L, targeting proteins to the lysosome. If the mannose residues on newly synthesized proteins are
phosphorylated in the endoplasmic reticulum, this marks the protein as destined for the lysosome. See book page 169.
6. Phosphorylation of STAT proteins.
Your Answer:
Answer: C, direct activation of a transcription factor. When STAT proteins are phosporylated on tyrosine residues by
JAK tyrosine kinases, they dimerize because each monomer has an SH2 domain that binds phosphotyrosine on its partner.
The STAT:STAT dimer is an active transcription factor. See book page 264.
7. Phosphorylation of the membrane lipid phosphatidylinositol 4,5 bisphosphate (PIP2) to yield
phosphatidylinositol 3,4,5 trisphosphate (PIP3).
Your Answer:
Answer: G, recruitment to the plasma membrane of proteins with PH domains, including protein kinase B. See book page 263.
Although this will usually reduce the likelihood that a cell will initiate apoptosis (answer H) that is a more indirect effect of PIP3
synthesis so G is the better answer.
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