Homeostasis and cell signalling (easy)

Question 1

W.R.T. diagram, describe GPCR structure [5]

Answer 1

1. 7-pass transmembrane protein; 7 alpha-helices connected by 3 intracellular + 3 extracellular peptide loops
2. Interactions with PM
   » hydrophobic interactions
   » hydrogen bonds, ionic bonds
3. R group interactions
   A. Fold in specific 3D conformation that is complementary in S/C
   B. Form temporary interactions

> > Intracellular domain has G protein binding site
Extracellular domain has ligand binding site

Question 2

Compare activation of G protein vs relay proteins

Answer 2

1. G protein activated upon binding of GTP which displaces GDP
2. Relay proteins phosphorylated by kinases

Question 3

Define signal amplification [1]

Answer 3

Each activated molecule can activate many molecules in the next step