User:Max Lein/Sandbox: Difference between revisions

Line 35:

5. Glycogen storage site.

There are two forms of the enzyme, designated as 'A' and 'B', that are controlled hormonally. The 'B' form is converted into the 'A' form by phosphorylase kinase, which catalyzes the addition of phosphate from ATP to Ser14 near the N-terminus. This represents the final step in a signal transduction cascade in response to the hormone epinephrine, associated with the 'fight-or-flight' response and causing an increase in available energy to the organism as a whole. The N-terminus contains a high percentage of basic residues, which interact favorably with a pocket of acidic residues in the 'B' form. Once Ser14 is phosphorylated, the N-terminus is forced ~50Å away from the acidic residues, settling into a region with ~~several arginine side chains~~. The enzyme phosphatase is able to remove the phosphate and return GP to form 'B'.

There are two forms of the enzyme, designated as 'A' and 'B', that are controlled hormonally. The 'B' form is converted into the 'A' form by phosphorylase kinase, which catalyzes the addition of phosphate from ATP to Ser14 near the N-terminus. This represents the final step in a signal transduction cascade in response to the hormone epinephrine, associated with the 'fight-or-flight' response and causing an increase in available energy to the organism as a whole. The N-terminus contains a high percentage of basic residues, which interact favorably with a pocket of acidic residues in the 'B' form. Once Ser14 is phosphorylated, the N-terminus is forced ~50Å away from the acidic residues, settling into a region with R69 and R45' (prime denotes a residue from the adjacent subunit). The enzyme phosphatase is able to remove the phosphate and return GP to form 'B'.

In addition, the 'A' and 'B' forms can be regulated futher by small molecules in the cell. This allows individual cells to ignore the hormonal signal if they already have enough available energy (at high concentrations of glucose derivatives or ATP, designated as the 'R' state), or activate GP without a hormonal signal when energy for the individual cell is needed (high concentrations of AMP, designated as the 'T' state).

In addition, the 'A' and 'B' forms can be regulated futher by small molecules in the cell. This allows individual cells to ignore the hormonal signal if they already have enough available energy (at high concentrations of glucose derivatives or ATP, designated as the 'T' state for low substrate affinity), or activate GP without a hormonal signal when energy for the individual cell is needed (high concentrations of AMP, designated as the 'R' state for high substrate affinity).

==Links==

User:Max Lein/Sandbox: Difference between revisions

Navigation menu

Page actions

Page actions

Personal tools

Navigation

Search

Tools

@@ Line 35: / Line 35: @@
 . Glycogen storage site.
-There are two forms of the enzyme, designated as 'A' and 'B', that are controlled hormonally.  The 'B' form is converted into the 'A' form by phosphorylase kinase, which catalyzes the addition of phosphate from ATP to Ser14 near the N-terminus.  This represents the final step in a signal transduction cascade in response to the hormone epinephrine, associated with the 'fight-or-flight' response and causing an increase in available energy to the organism as a whole.  The N-terminus contains a high percentage of basic residues, which interact favorably with a pocket of acidic residues in the 'B' form.  Once Ser14 is phosphorylated, the N-terminus is forced ~50Å away from the acidic residues, settling into a region with several arginine side chains.  The enzyme phosphatase is able to remove the phosphate and return GP to form 'B'.
+There are two forms of the enzyme, designated as 'A' and 'B', that are controlled hormonally.  The 'B' form is converted into the 'A' form by phosphorylase kinase, which catalyzes the addition of phosphate from ATP to Ser14 near the N-terminus.  This represents the final step in a signal transduction cascade in response to the hormone epinephrine, associated with the 'fight-or-flight' response and causing an increase in available energy to the organism as a whole.  The N-terminus contains a high percentage of basic residues, which interact favorably with a pocket of acidic residues in the 'B' form.  Once Ser14 is phosphorylated, the N-terminus is forced ~50Å away from the acidic residues, settling into a region with R69 and R45' (prime denotes a residue from the adjacent subunit).  The enzyme phosphatase is able to remove the phosphate and return GP to form 'B'.
-In addition, the 'A' and 'B' forms can be regulated futher by small molecules in the cell.  This allows individual cells to ignore the hormonal signal if they already have enough available energy (at high concentrations of glucose derivatives or ATP, designated as the 'R' state), or activate GP without a hormonal signal when energy for the individual cell is needed (high concentrations of AMP, designated as the 'T' state).
+In addition, the 'A' and 'B' forms can be regulated futher by small molecules in the cell.  This allows individual cells to ignore the hormonal signal if they already have enough available energy (at high concentrations of glucose derivatives or ATP, designated as the 'T' state for low substrate affinity), or activate GP without a hormonal signal when energy for the individual cell is needed (high concentrations of AMP, designated as the 'R' state for high substrate affinity).
 ==Links==