Integrins Flashcards
How does talin bind to integrins?
Via its N terminal end and C terminal end binds actin.m
Describe the binding of vinculin to talin.
Long c terminal domain of talin has multiple binding sites for vinculin.
When actin pulled by myosin motors tension stretches talin road, exposing the hidden vinculin binding sites - vinculin can now recruit and organize additional actin filaments.
which model of activation is better supported?
inside out.
Describe a Lamellipodia.
Membrane ruffles forming in freely migrating cells.
2D sheet with cross-linked network of actin filaments
Rac promotes actin polymerisation at leading edge.
Cofilin bonds ADP actin at rear - promoting disassembly.
How are stress fibres formed?
Rho promotes bundling of actin filaments with myosin II –> stress fibres and integrin clustering –> focal adhesions.
What are the models for integrin dynamics in migrating cells?
ORIGINAL - endocytosed at rear into EEs then recycling endosomes to leading edge.
CURRENT - constantly endocytosed and recycled at leading edge of migrating cells to permit more rapid response to extracellular cues.
Give an example of two different types of integrins.
A1B1 - collagens, lamins are ligands
AVB6 - fibronectin (found in proliferating epithelial cells).
What experiments have been done with FAK?
Cells lacking it have larger and more stable FAs and migrate more slowly
FAK must have role in controlling FA assembly and adhesion.
What is the role of the FAK-Src complex?
Phosphorylation other adhesion proteins (paxillin etc)
And proteins controlling GTPase activity to modulate actin cytoskeleton.
What is an invasion assay?
Matrix proteins placed on filter with 8um pores
Place chemoattractant under filter
Cells fall through if can degrade ECM.
What is a filopodia?
Parallel 1D F actin bundle
Sensing in cells
Cdc42 activates them.
What are the three levels of signalling in cell migration?
Environmental cues
Signal transmission (2nd messenger, signal transducer, RhoGTPases)
Cellular response
