Quiz 3 Flashcards
How does high energy charge regulate PFK1 in the muscles during glycolysis?
This is during rest. ATP allosterically regulates PFK1 in a negative way. It is inhibited. Slows down AMP reverses inhibitory effect on ATP
High energy charge, ATP turns it off & AMP turns it on
How does low charge regulate PFK1 in the muscles during glycolysis?
Increase AMP
Positively regulates PFK1
How does energy charge effect PFK1 in the liver?
There’s no effect. PFK doesn’t care about energy charge in the liver.
How does fructose 2,6-BP regulate PFK1?
fructose 2,6-biphosphotate stimulates PFK1 b/c now need more ATP
Happens in the liver
Inhibits fructose 2,6-biphosphatase
How does fructose 6-phosphate regulate PFK?
It stimulates PFK1 & inhibits 1,6-biphosphate
At high energy charge, will PFK1 be on or off?
OFF
At high energy charge, will pyruvate kinase be on or off?
OFF
When there’s lots of 2,6-biphosphate in the cell, will PFK be on or off?
ON
How is hexokinase regulated?
It’s inhibited by glucose 6-phosphate when PFK is inhibited
High levels of glucose 6-phosphate negatively inhibits it
Not directly effected by energy charge
Found in muscles
How is pyruvate kinase regulated by energy charge?
high energy charge, ATP turns it off
activated by fructose 1,6-biphosphate
Low energy charge means?
positive regulation of PFK & pyruvate kinase
How is pyruvate kinase regulated in the liver?
Same allosteric control
High levels of ATP, turn down pyruvate kinase
-
2 ways*
1) It’s regulated allosterically by ATP
2) it’s phosphorylated in the presence of low glucose levels
When is pyruvate kinase phosphorylated?
when there is low blood glucose
How is glucokinase inhibited?
Not inhibited by glucose 6-phospate
Phosphorylates glucose when concentrations are high to provide glucose 6-phophate for glycogen synthesis and formation of fatty acids
Low affinity for glucose - gives brain and muscle first call on glucose when supplies are limited and insures it’s not wasted when it’s in abundance
