Receptor Mechanisms 3

Question 1

What is dimerisation of receptors involved in?

Answer 1

•	Cell growth
•	Division 
•	Differentiation 
•	Survival 
•	Migration 
 Inappropriate activation is associated with disease particularly cancer

Question 2

What happens when a ligand binds to a receptor in a tyrosine kinase receptor?

Answer 2

Induces dimerisation

2 monomers phosphorylate the tyrosine residues
Enzymes bind to the C-terminal/ cellular proteins which induces a biological response

This is an example of auto phosphorylation

Question 3

What do we mean by tyrosine kinase activity?

Answer 3

• Dimerisation brings two receptor molecules together allowing phosphorylation of specific tyrosine residues
• Not all tyrosine residues in the receptor molecule are phosphorylated
• The phospho-tyrosine together with surrounding amino acids are recognised by SH2 domains of other proteins allowing them to bind and undergo activation.
• The amino acids are shown as the coloured circles, the enzyme recognises specific tyrosine residues within in the receptor molecules. Only one of the tyrosine residues have been phosphorylated.
• The surrounding amino acids form a domain and motif that the enzymes can recognise.
• The amount of phosphorylation effects how much effect that receptor has.
• SH2 is a format – allows proteins to dock to the tyrosine residues.