Glucose Uptake and Exercise (LOIL1)

Question 1

what are the 3 questions about how we keep the human alive ?

Answer 1

1. how to break down the nutrients and extract the energy to maintain cellular functions ?
2. how to store the energy and maintain the cell structures ?
3. how to transport the molecules in and out of there cell ?

Question 2

what can move via passive diffusion ?

Answer 2

1. small non-polar ions
2. hydrophobic molecules (such as steroid hormones)
3. water (to some degree)

Question 3

what are ‘Solute Carrier (SLC ) Transporters’ ?

Answer 3

the largest group of transporters classified into 65 different gene families with 458 different transporters in humans

Question 4

SLC transport what 6 things?

Answer 4

1. monosaccharides
2. amino acids
3. fatty acids
4. vitamins
5. neurotransmitters
6. inorganic/metal ions

Question 5

what can SLC inhibitors be used for ?

Answer 5

SLC inhibitors can be used as drugs for the treatment od diseases (eg - SLC5A2 for hyperglycaemia)

Question 6

state what it is meant by the key term - symporter

Answer 6

a symporter is a transporter which co-transports molecules in the same direction

Question 7

state what it is meant by the key term - antiporter

Answer 7

an antiporter is a transporter which co-transports molecules in opposite directions

Question 8

state 7 examples of SLC transporters

Answer 8

1. facilitated transporter
2. antiporter
3. symporter
4. orphan transport
5. rocker switch
6. gated pore
7. elevator

Question 9

transporter kinetics law = ?

Answer 9

transporter kinetics law = enzymes kinetic laws

Question 10

what are the 2 kinetics laws you need to remember for transporters ?

Answer 10

1. affinity of the transporter for its substrate = Km (Michaelis constant)
2. velocity of the substrate across the CSM = Vmax (maximum rate of reaction)

Question 11

state the 3 types of transport inhibition

Answer 11

1. competitive
2. non-competitive
3. allosteric

Question 12

how is glucose transported across cell membranes (2 ways)

Answer 12

1. secondary active transport

2. facilitated diffusion

Question 13

the mode of glucose transport across a CSM depends upon what ?

Answer 13

depends upon the concentration of glucose within the interstitial fluid

Question 14

both modes of glucose transport are performed by SLC transporters, but from different families. state the 2 transporters used

Answer 14

1. SLC2 family - facilitated diffusion

2. SLC5 family - secondary active transport

Question 15

what family is the following transporter part of - sodium-glucose co-transporter (SGLT)

Answer 15

SLC5 family

Question 16

state the names of the 2 SGLT’s (sodium-glucose co-transporter)

Answer 16

1. SGLT1

2. SGLT2

Question 17

state 3 facts about SGLT’s (sodium-glucose co-transporters)

Answer 17

1. they require the electrochemical gradient of Na+ to transport glucose against its concentration gradient
2. SGLT are secondary active transport transporters
3. they require ATP (energy) and Na+/K+ ATPase in order to function

Question 18

state 1 fact about - ‘Sodium-Glucose Co-Transporter (SGLT) function’

Answer 18

they are exclusively present in tissues responsible for absorption/reabsorption of glucose from nutrients (small intestine SGLT1) or from urine (kidney SGLT2/SGLT1)

Question 19

state what it is meant by the key term - SGLT2 inhibitors

Answer 19

SGLT2 inhibitors are a new therapeutic drug for glucose control in people with diabetes (T2D and T1D)

Question 20

state the two families that the following transporter belongs to - ‘Facilitative Glucose Transporters (GLUT1) family’

Answer 20

1. Solute Carrier Gene Family (SLC2a)

2. Major Facilitators Family (MFS) - which contains more than 500 members

Question 21

state the 5 types of class 1 Facilitative Glucose Transporters

Answer 21

1. GLUT 1
2. GLUT 2
3. GLUT 3
4. GLUT 4
5. GLUT 14

Question 22

state the 4 types of class 2 Facilitative Glucose Transporters

Answer 22

1. GLUT 5
2. GLUT 7
3. GLUT 9
4. GLUT 11

Question 23

state the 5 types of class 3 Facilitative Glucose Transporters

Answer 23

1. GLUT 6
2. GLUT 8
3. GLUT 10
4. GLUT 12
5. HMIT (GLUT 13)

Question 24

state the following for the GLUT transporter stated - GLUT 1

1) tissue
2) special feature
3) substrate specificity

Answer 24

1. ubiquitous, red cells
2. N/A
3. glucose, galactose

Question 25

state the following for the GLUT transporter stated - GLUT 14 1) tissue 2) special feature 3) substrate specificity

Answer 25

1. neurones 2. N/A 3. glucose, galactose

Question 26

state the following for the GLUT transporter stated - GLUT 4 1) tissue 2) special feature 3) substrate specificity

Answer 26

1. fat, muscle 2. trafficking - regulated by insulin (LL motif) 3. glucose

Question 27

state the following for the GLUT transporter stated - GLUT 2 1) tissue 2) special feature 3) substrate specificity

Answer 27

1. intestine, liver, kidney, Beta cell 2. mediates both uptake and efflux 3. glucose, galactose, fructose

Question 28

state the following for the GLUT transporter stated - GLUT 5 1) tissue 2) special feature 3) substrate specificity

Answer 28

1. intestine, sperm 2. found primarily in fructose metabolising tissue 3. fructose, glucose

Question 29

state the following for the GLUT transporter stated - GLUT 7 1) tissue 2) special feature 3) substrate specificity

Answer 29

1. intestine 2. apical membrane targeting 3. glucose, fructose

Question 30

state the following for the GLUT transporter stated - GLUT 9a/9b 1) tissue 2) special feature 3) substrate specificity

Answer 30

1. kidney BLM 2. liver expression co-localises with GLUT2, but not kidney 3. glucose, fructose

Question 31

state the following for the GLUT transporter stated - GLUT 11 1) tissue 2) special feature 3) substrate specificity

Answer 31

1. muscle, heart, fat, placenta, kidney, pancreas 2. 3 isoforms (A, B and C) 3. glucose, fructose

Question 32

state the following for the GLUT transporter stated - GLUT 6/9 1) tissue 2) special feature 3) substrate specificity

Answer 32

1. brain, spleen 2. has LL targeting motif 3. glucose

Question 33

state the following for the GLUT transporter stated - GLUT 8 1) tissue 2) special feature 3) substrate specificity

Answer 33

1. testes, fat, liver, brain, spleen 2. has LL targeting motif 3. glucose, fructose

Question 34

state the following for the GLUT transporter stated - GLUT 10 1) tissue 2) special feature 3) substrate specificity

Answer 34

1, heart, lungs 2. N/A 3. glucose, galactose

Question 35

state the following for the GLUT transporter stated - GLUT 12 1) tissue 2) special feature 3) substrate specificity

Answer 35

1. insulin-sensitive tissue 2. has LL targeting motif 3. glucose, fructose, galactose

Question 36

state the following for the GLUT transporter stated - HMIT / GLUT 13 1) tissue 2) special feature 3) substrate specificity

Answer 36

1. brain 2. proton-coupled substrate movement 3. myoinositol (a type of sugar)

Question 37

where is GLUT 4 mainly expressed ?

Answer 37

skeletal muscle, heart and adipose tissue

Question 38

what is GLUT 4 ?

Answer 38

GLUT 4 is a highly specialised glucose transporter which is regulated by insulin and contraction

Question 39

what was GLUT 4's original name ?

Answer 39

insulin-responsive glucose transporter (IRGT)

Question 40

what does GLUT 4 do in response to insulin stimulation ?

Answer 40

GLUT 4 translocates/traffics to the CSM in response to insulin stimulation or muscle contraction

Question 41

what does GLUT 4 also possess ?

Answer 41

GLUT 4 has a specialised intracellular storage compartment called - GLUT 4 Storage Compartment (GCS) - from there it is recruited to the CSM

Question 42

what do deficits in insulin-stimulated GLUT 4 trafficking result in ?

Answer 42

deficits in insulin-stimulated GLUT 4 trafficking is an early manifestation to insulin resistance and the pre-diabetic phase of T2D