Lecture 2 - Insulin and Friends

Question 1

what can goldfish convert lactate into

Answer 1

ethanol

Question 1

insulin is synthesised as a pre-pro-peptide, what is this

Answer 1

small protein

Question 2

what is the pre sequence in insulin responsible for

Answer 2

the export from the cytosol of the cell
- in this case to secretory granules

Question 3

what does the pro-sequence of insulin seem to be important for (and what happens to it)

Answer 3

proper folding of insulin and it is removed

Question 4

what bonds and structure interactions does insulin have

Answer 4

disulfide bonds (C-C) as well as secondary and tertiary structure interactions (covalent linkages)

Question 5

where is insulin made

Answer 5

made in the islets of Langerhans in the pancreas (B cells)

Question 6

what do alpha cells in the pancreas produce

Answer 6

glucagon

Question 7

what are two of the endocrine hormones produced in the pancreas

Answer 7

insulin and glucagon

Question 8

insulin typically forms hexamers with what in B cells and what does this mean

Answer 8

Zn = causes insulin to be packed very tightly together and held into hexamers

Question 9

insulin forms what in the blood

Answer 9

monomers in blood

Question 10

circulating insulin interacts with what

Answer 10

receptors on some tissues (fat, muscle and liver etc)

Question 11

the insulin receptor is synthesised as one protein and then what happens for its full function form (what does it form)

Answer 11

it is cleaved (modified) for full function (forms a dimer)

Question 12

what gives rise to different insulin receptor isoforms

Answer 12

splicing variants during mRNA processing

Question 13

how many splices is the insulin receptor split into

Answer 13

3

Question 14

where does the largest splice (A chain) of the insulin receptor sit

Answer 14

sits outside the cell and folds

Question 15

where does the B chain of the insulin receptor sit

Answer 15

the first part of B chain is in the membrane, other part is inside the cell

Question 16

insulin is a what on the surface of the cell

Answer 16

dimer

Question 17

what are the three domains of the insulin receptor

Answer 17

• extracellular domain
• transcellular domain
• cytosolic domain

Question 18

what will activate the insulin receptor

Answer 18

insulin binding

Question 19

when there is no ligand (insulin) present at the receptor what does the receptor do

Answer 19

remains inactive

Question 20

what does binding of insulin cause to the receptor

Answer 20

structural changes and activates the receptor

Question 21

specifically what part of the receptor is changes when insulin binds

Answer 21

tyrosine kinase domain

Question 22

in a normal body insulin is released from where and in response to what

Answer 22

insulin is released from B cells in response to blood glucose

Question 23

in a normal body when the insulin receptor is stimulated what happens

Answer 23

receptor is stimulated, GLUT4 moves to the cell surface to transport glucose

glucose is taken up by the cell

Question 24

what is the problem with insulin in type 1 diabetics and what is the cause of this

Answer 24

no functional insulin, autoimmune disease or variant insulin

Question 25

what is the problem with insulin in type 2 diabetics and what is the cause of this

Answer 25

reduced receptor sensitivity, obesity or rare genetic receptor variants

(receptor not responding to insulin)

Question 26

what does the uptake of glucose stimulate

Answer 26

oxidative metabolism and ATP production

Question 27

increased metabolic activity stimulates the conversion of what and the release of insulin

Answer 27

conversion of proinsulin and release of insulin

Question 28

what is the function of GLUT4 and where is it found

Answer 28

insulin-dependent glucose uptake, found in striated muscle and adipose tissue

Question 29

what is the broad process called that GLUT4 does

Answer 29

endo and exocytosis

Question 30

what is the function of GLUT2 and where is it found

Answer 30

largely responsible for insulin-independent uptake of glucose (it happens on its own)

found in kidney, liver, pancreatic B cells, basolateral membrane of small intestine

Question 31

what is endocytosis

Answer 31

internalising molecules, particles, or fluids from the external environment by engulfing them into membrane-bound vesicles

Question 32

what is exocytosis

Answer 32

cells release molecules, particles, or fluids from internal vesicles into the extracellular environment