Lecture 6 - Focal Adhesion Complexes

Question 1

What are Focal Adhesion Complexes?

Answer 1

Complexes which link the actin cytoskeleton to the ECM via Integrin (Integrin-dependent Adhesion)

Question 2

Define Integrins

Answer 2

Transmembrane Receptors which form a physical link between the actin cytoskeleton and ECM via a large set of adaptor proteins

Question 3

What is the General Structure of Integrins

Answer 3

Transmembrane Heterodimer consisting of two non-covalently associated glycoprotein subunits (a/B)

Question 4

What is Meant By “Integrin Activation is a form of allosteric activation”?

Answer 4

When Integrin binds/releases a ligand it undergoes a conformational change that impacts both the EC and IC domains

Question 5

How do Adaptor Proteins form physical link between ECM and Actin Cytoskeleton?

(2 Points)

Answer 5

• They bind to the Intracellular C-terminal end of Integrin in response to Extracellular portion binding to specific aa sequences of ECM proteins (e.g., Fibronectin)
• Adaptor proteins then form a complex to link Integrin to actin cytoskeleton

Question 6

How do Integrins produce strong adhesions?

Answer 6

Integrins cluster together to form a plaque where multiple cytoskeletal filaments are anchored in close proximity

Question 7

Why are FAC described as dynamic structures?

(2 Points)

Answer 7

• They can assemble/disassemble as required to permit cell movement, or in response to ECM
• Many different FAC components have been identified, with a complex of network of components being possible (i.e., composition can vary between/within cells)