GPCR's

Question 1

What do G-Protein coupled receptors consist of?

Answer 1

GPCRs consist of a single polypeptide that is folded into a globular shape and embedded in a cell’s plasma membrane - 7 segments span the width of the membrane = “7-transmembrane receptors”

Question 2

GPCR’s interact with ________ in the plasma membrane

Answer 2

GPCR’s interact with G-proteins in the plasma membrane

Question 3

What are G-Proteins?

Answer 3

Specialized proteins that have the ability to bind the nucleotides Guanosine-triphosphate (GTP) and Guanosine-diphosphate (GDP)

Question 4

G-Proteins that associate with GPCR’s are _______ (have three subunits)

Answer 4

G-Proteins that associate with GPCR’s are heterotrimeric (have three subunits)

1. alpha subunit
2. beta subunit
3. gamma subunit

Question 5

What are the three subunits of the G-Proteins that associate with GPCR’s?

Answer 5

1. alpha
2. beta
3. gamma

• Alpha and gamma subunits are attached to plasma membrane via lipid anchors

Question 6

Which two subunits of the G-Protein are attached to the plasma membrane and how?

Answer 6

Alpha and gamma subunits are attached to plasma membrane via lipid anchors

Question 7

Which subunit of the G-Protein binds to either GDP or GTP and under what conditions?

Answer 7

Alpha subunit

• Active (GTP)
• Inactive (GDP) - absence of signal