1 - Intro to Advanced Molecular Biology

Question 1

What is short range signalling?

Answer 1

contact dependent
e.g. notch pathway signalling, spaces R8 photoreceptors in Drosophila eye disc morphogenic furrow
Neurons - can do one to one signalling

Question 2

What is paracrine signalling?

Answer 2

a cell produces a signal to induce changes in nearby cells, altering the behaviour of those cells
e.g. Hedgehog expression stimulates decapentaplegic (DPP) ligand expression - is secreted by a strip of cells in the middle of drosophila wing disc
activate the downstream transcription factor Mad

Question 3

How does adrenaline act?

Answer 3

produced by adrenal glands
acts via adrenergic receptors
produce a wide range of physiological responses
e.g. fight/ flight
endocrine signalling - long-range communication - carried by circulatory system

Question 4

How do cells respond to signalling?

Answer 4

• change the structure of an existing protein e.g. Ion channel (very fast)
• changing the post translational modification e.g. phosphorylation (quite fast)
• Changing protein levels via gene expression (relatively slow)

Question 5

Example of defect in signalling regulation:

Answer 5

Myeloproliferative Neoplasms -
diseases of blood marrow and blood

JAK2 V617F mutation in the regulatory ‘pseudokinase’ domain of JAK2
Gain of function
is associated with >95% of polycythemia vera (blood cancer)

Chronic myeloid leukemia -
BCR-Abl fusion (of genes) protein - causes sustained ABL tyrosine kinase expression by Bcr
promoter/ enhancer region leading to CML
both treated by kinase inhibitors

Question 6

How is signalling regulated in vivo?

Answer 6

many stages - extracellular/ ligand/ receptor
positive + negative feedback mechanisms

Question 7

What is required for fast responses?

Answer 7

rapid turnover of the effector
making + immediately destroying proteins to achieve rapid turnover = very wasteful process
problem fixed by adding post-translational modification
-act as switch that activates/ inactivated protein function

Question 8

What are the 2 types of protein kinase in eukaryotes?

Answer 8

• serine/threonine kinase
• tyrosine kinases

Question 9

What are the different types of kinase inhibitors?

Answer 9

Type 1: bind to the active conformation of Kinase w/ aspartate residue of the DFG motif pointing into the ATP binding pocket

Type II: bind + stabilise inactive conformation of kinase
with flipped aspartate residue facing outward of binding pocket

Type III: occupy the allosteric pocket that is adjacent to the ATP binding pocket - does not overlap

Type IV: bind to allosteric pocket remote from the ATP-binding pocket