Glycogen biochem

c ring

Rotates with protons to drive the rotor. Spins 360 degrees.

Peripheal stalk

Made of the a, b₂ and δ subunits. It stabilizes the knob so that it doesn’t spin.

a

Which ATP synthase subunit is where protons enter and exit?

Rotor

Composed of the γ and ε subunits, tightly associated with each other. Spins 360 degreees in 120 degree increments. γ is inside the barrel of the α and β subunits, associating with them.

Knob

α and β subunits tightly assoicated as dimers. Stationary.

beta

Which subunit of ATP synthase is the catalytic portion?

ATP-ADP translocase

This enzyme enables the exchange of cytoplasmic ADP for mitochondrial ATP. It is powered by proton-motive force.

ATP synthasome

A complex of ATP-ADP translocase, phosphate carrier, and ATP synthase.

glycogenin

A self glycoslatying core protein and enzyme that acts as the essenital primer to initiate glycogen synthesis

Phosphorylase

Works on straight chain pieces, starts at the nonreducing end and chews off glucose-1-phosphate until the chain is four residues from a branch. A tranferase. Breaks alpha-1,4-glycosidic bonds.

Phosphoglucomutase

Converts the G1P to G6P

Transferase

Part of the branching enzyme. Snips off the three glucose residues on a branch and adds them to a straight chain. Breaks and makes alpha-1,4-glycosidic bonds.

alpha 1,6 glucosidase

Breaks the branching glucose residue off and releases a glucose monomer. It uses water and is a hydrolase. It breaks alpha 1,6 glycosidic bonds.

glucose 6 phosphatase

What enzyme for glycogenolysis is present in the liver but absent in the skeletal muscle?

allosterically

Phosphorylase’s R and T state are regulated (hormonally/allosterically)

Unphosphorylated, phosphorylated

When phosphorylase is (phosphorylated/unphosphorylated) it favors T state, and when it is (phosphorylated/unphosphorylated) it favors R state.

glucose and ATP

What affectors promote the T state of phosphorylase?

AMP

What affectors promote the R state of phosphorylase?

R

The liver favors which state (R/T) of phosphorylase?

T

The skeletal muscle favors which state (R/T) of phosphorylase?

a

The default phosphorylase conformation in the liver is phosphorylase (a/b)

b

The default phosphorylase conformation in the skeletal muscle is phosphorylase (a/b)

b, a

When glycogen synthase is phosphorylated, it is in conformation (a/b), it’s inactive state. When glycogen synthase is dephosphorylated, it is in conformation (a/b), it’s active state.