Cell Signalling V

Question 1

How is a chemical signal translated?

Answer 1

Arrival of a signal
Activation of the receptor
Interaction /activation of different types proteins
Intracellular Signalling cascades

Question 2

How may an enzyme specific activity be altered?

Answer 2

Alteration of the primary structure of the protein

Alteration of tertiary and quaternary structure

Question 3

What other ways facilitate the changes of the conformation of a protein?

Answer 3

Change in pH
A change in the reduction/oxidation environment
The addition and removal of phosphate –Phosphorylation and de-phosphorylation

Question 4

Phosphorylation alters the activity of?

Answer 4

an enzyme/protein

Essential for the coordinated control of metabolic pathways to avoid futile cycles

Question 5

how is phosphorylation ideal?

Answer 5

process is ideal as a means of regulation in response to a cellular signal- Fast interaction

Question 6

What is it called when a protein can be phosphorylated on more than one site and by more than one kinase?

Answer 6

Conevergence of several signalling pathways

Question 7

What is it called when kinases are capable of phosphorylating many proteins?

Answer 7

Consensus sequence

Question 8

What is it easy to predict by using bioinformatic analysis?

Answer 8

Phosphorylation site

Question 9

What is cAMP-dependent protein kinase-Protein kinase A (PKA)?

Answer 9

PKA exists in inactive tetrameric state , it dissociates upon activation to release two catalytic subunits.

Question 10

What is Protein kinase C?

Answer 10

One of the most important protein kinases

Question 11

What was the serine/threonine protein kinase C (PKC) family was first identified as?

Answer 11

intracellular receptor(s) for the tumor promoting agents phorbol esters

Question 12

What do the classical (or conventional) PKC isoforms α, βI, βII, γ take part in?

Answer 12

Require negatively charged phospholipids like phosphatidylserine, diacylglycerol and calcium for optimal activity

Question 13

What do the novel PKC isoforms δ, ɛ, θ, η, μ take part in?

Answer 13

Require negatively charge phospholipids and diacylglycerol but no calcium for optimal activity

Question 14

What do the atypical PKC isoforms λ and ζ take part in?

Answer 14

only require negatively charged phospholipids but neither calcium nor diacylglycerol for optimal activity

Question 15

What is the human genome is estimated to encode more than?

Answer 15

100 PTPs, which can be divided into eleven sub-groups according to their structural and functional characteristics.