Glucose Homeostasis And Glycogen Metabolism

Front 1

basal glucose uptake transporters found in all mamailan tissues

Back 1

GLUT 1 and GLUT 3

Front 2

membrane transporter that uses active transport

Back 2

SGLT1

Front 3

membrane transporter found only in the liver and pancreatic B cells

Back 3

GLUT 2

Front 4

transporter that has a HIGH Km for glucose

Back 4

GLUT 2

Front 5

which transporter carries glucose out into the bloodstream when entrocyte glucose levels get high

Back 5

GLUT 2

Front 6

where is insulin released from

Back 6

Pancreatic B cells

Front 7

which transporter is cotrolled by Insulin?

Back 7

GLUT 4

Front 8

where are GLUT 4 transporters found?

Back 8

adipose tissues (fat cells) and skeletal muscle

Front 9

how do skeletal muscle and adipose tissue store glucose

Back 9

glycogen and fat

Front 10

which transporters uptake fructose?

Back 10

GLUC 5

Front 11

two transporters on apical side of intestine cells?

Back 11

GLUT 5 and SGLT1

Front 12

expressed in tumor cells and induces GLUT 1 and GLUT 3 and key enzymes in glycolysis

Back 12

HIF- 1 Hypoxia Inducible Transcription Factor

Front 13

how does the cell trap glucose?

Back 13

hexokinase and glucokinase

Front 14

converts glucose to G6P in all tissues

Back 14

Hexikinase

Front 15

convert glucose to G6P in liver and Pancreatic B Cells

Back 15

Glucokinase

Front 16

which has higher Km for glucose? Hexokinase or Glucokinase?

Back 16

hexokinae- .1nM
glucokinase- much higher

Front 17

what does hexokinase use as a substrate and why?

Back 17

Mg-ATP...neutralizes negative charge of ATP

Front 18

how does cell shut off hexokinase?

Back 18

is inhibited by G6P

Front 19

where is glucokinase present?

Back 19

Liver and Pancreatic B Cells

Front 20

The 3 fates of G6P

Back 20

glycolysis, glucose, pentose phosphate

Front 21

glycogen linkages

Back 21

alpha (1,4) and alpha (1,6)

Front 22

why store as glycogen and not glucose?

Back 22

extreme osmotic advantage

Front 23

one free reducing end in glycogen is added to

Back 23

glycogenin

Front 24

major enyme that breaks down glygogen

Back 24

GLYCOGEN PHOSPHORYLASE

Front 25

glycogen phosporylase breaks glycogen down to...

Back 25

G1P

Front 26

cofactor that works with glycogen phosphorylase

Back 26

pyridoxal phosphate

Front 27

product left by glycogen phosphorylae

Back 27

limit dextrin

Front 28

breaks down limit dextrins

Back 28

Debranching Enzyme

Front 29

converts G1P to G6P

Back 29

Phosphoglucomutase

Front 30

Phosphoglucomutase adds P using which amino acid?

Back 30

Serine

Front 31

takes P off of G6P

Back 31

Glucose-6- Phosphatase

Front 32

where is Glucose-6- Phosphate located?

Back 32

luminal surface of ER

Front 33

path of glucose to get the P taken off

Back 33

1)goes to ER to be acted on by Glucose 6-Phosphatase
2) back to cytosol
3) builds up inside liver cell
4)diffuses back into blood through GlUT 2 transporters

Front 34

why is it advantageous for liver to have glucokinase?

Back 34

If had hexokinase, all of glucose would be Phosphorylated right away- need some to go out in the blood

Front 35

How does Debranching enzyme work

Back 35

1) Take a piece off of alpha (1,6) branch and installs it in another place
2) Hydrolysis step- takes last part of branch that is left...uses water and FREE GLUCOSE is released

Front 36

where could someone without Glucose 6 Phosphatase still get glucose?

Back 36

1 free glucose released by Debranching Enzyme

Front 37

why is Glycogen Phosphorylase rxn not reversibe?

Back 37

because of low ratio of G1P campared to P ratio.

Front 38

G6P to G1P

Back 38

Phosphoglucomutase

Front 39

GIP is activated by

Back 39

UDP- Glucose Pyrophosphorylase

Front 40

what is cofactor used to drive the UDP- Glucose Pyrophosphorylase reaction forward

Back 40

Pyrophosphatase (splits pyrophosphate irreversibly).

Front 41

catalyzes the elongation of non-reducing termini of glycogen

Back 41

Glycogen Synthase

Front 42

what type of linkages does Glycogen Synthase form?

Back 42

alpha (1,4)

Front 43

how long does chaing have to be for glucose to be added to glycogen chain by Glycogen Synthase? attached to which structure?

Back 43

4 units
UDP glucose specifically

Front 44

Glycogen Synthase is dephosphorylated (activated) by which enzyme?

Back 44

PP1

Front 45

generalized enzyme that regenerates triphosphate molecules with the use of ATP

Back 45

nucleoside diphosphate kinase

Front 46

small protein that is a dimer at the center of glycogen molecule

Back 46

glycogenin

Front 47

glycogenin contains what residue?

Back 47

tyrosine

Front 48

glycogenin attaches how many glucose molecules? what is donar?

Back 48

8
UDP glucose

Front 49

after glycogenin and glycogen synthase have made chain at least ll units, which enzyme takes over?

Back 49

Branching Enzyme

Front 50

how does Branching Enzyme work?

Back 50

can move a 7 glucose unit chain to a 6 position on a nearby chain...can't be closer than 4 units to another branch.

Front 51

Two VERY important enzymes that control blood glucose

Back 51

Glycogen Phosphorylase
Glycogen Synthase

Front 52

Things that increase glycogen breakdown
(4)

Back 52

epinephrine
glucagon
AMP
Ca

Front 53

Things that increase glycogen syntheis (4(

Back 53

Insulin
ATP
G6P
glucose

Front 54

active state of glycogen phosphorylase

Back 54

R state

Front 55

inactive state of glycogen phosphorylase

Back 55

T state

Front 56

hormones that control glycogen phosphorylase (glucagon, epinephrine, and insluin) work through:

Back 56

Phosphorylase Kinase

Front 57

takes off phosphate (opposes phosphorylase kinase)

Back 57

Protien Phsopate 1 (pp1)

Front 58

what is allosteric effector that can force phosphorylase a back into the inactive state (T state)

Back 58

glucose

Front 59

what is allosteric effector rhat can force phosphorylase b to the active state?

Back 59

AMP (signal that cell is using ATP- need more energy- must break down glycogen)

Front 60

mediator between phosphorylase b to phosphorylase a

Back 60

Phosphorylase Kinase

Front 61

Phosphorylase Kinase must be activated itself....how?

Back 61

1) being phosphorylated itself in the B subunit
2) Calcium binging to the sigma subunit

Front 62

what phosphorylates Phosphorylase Kinase?

Back 62

Protein Kinase A
(cAMP dependent protein kinase)

Front 63

catalyzed the undoing of phosphorylation by Protein Kinase A and phosporylase Kinase

Back 63

pp1

Front 64

cAMP dependent cascade
(in box)

Back 64

epinephrine- adenylate cyclase-cyclic AMP-Protein Kinase A

Front 65

2 additional steps for glycogen breakdown

Back 65

Phosphorylase Kinase- Phosphorylase a

Front 66

additional stop for glycogen synthesis

Back 66

Phosphorylates (deactivates) Glycogen Synthase...forms Glycogen Synthase Bi

Front 67

How else does epinephrine initiate glycogen breakdown?

Back 67

inhibits pp1....acts on Protein Kinase A to phosphorylate a binding protein..relases pp1.....also phosphorylates inhibitor-really shuts down pp1

Front 68

How does insulin stimulate glycogen breakdown?

Back 68

phosphorylates binding molecule in a different place..makes glycogen more accessible by pp1

Front 69

Two things that pp1 does to initiate glycogen synthesis

Back 69

forces Glycogen Phosphorylase A to form Glycogen Phosphorylase B (inactive state) by dephosphorylation
2) also dephosphorylates Glycogen Synthase (act9vates)

Front 70

when is pp1 activated

Back 70

when Glycogen Phosphorylase a is in the T State...phosphate is exposed and pp1 dephosphorylates it

Front 71

what mediates the stimulation of gluconeogenesis in the liver by glucagon and epinephrine?

Back 71

cAMP

Front 72

what recruits GLUT 4s to membrane in skeletal muscles for glucose uptake?

Back 72

Insulin

Front 73

Calcium in muscles cells activate what to stimulate glycogen breakdown in muscle cells?

Back 73

phosphorylase kinase