Flashcards in Cell cortex and locomotion Deck (19):
Where are actin filaments found in the cell?
throughout the cytoplasma, but concentrated ina region just below the plasma membrane in most cells
What is the cell cortex?
actin filaments are crossed linked into a supportive and strengthening network
gives cell their characteristic shape
What are actin filaments attached to the plasma membrane by?
various linker proteins
what are the Crawling cells?
Why do crawling cells reorganize their cell cortex?
utilize their MF and their interaction with other proteins to move
What is the leading edge?
front of moving cell , composed of two structures
What are the two structures of the leading edge?
What is the lamellipodia?
thin sheet like structure with dense network of F-actin in a single orientation with plus end at plasma membrane
What is the filopodia?
exporatory fibers, long thin with parallel bundles of 10-20 F-actin
How does the lamellipodia and filopodia move?
very dynamic forming and retracting rapidly
What is the molecular mechanism thought to be known for movement of cell?
1) cell pushes out front or leading edge
2)protrusions adhere to surface to form anchor
3)rest of cell uses anchorage point to pull cell forward
all steps involve actin and associated proteins
What does the initial steps of movement involve?
nucleating proteins - a type of ABP found at the plasma membrane promotes actin polymerization
When does integrins adhere to the surface?
when exploratory tip finds favorable environment
What are integrins?
transmembrane proteins that adhere to molecules in the extracellular matrix or on another cell
What do integrins also act with?
this gives the cell an anchor that spans from extracellular matrix to to the cytoplasmic cell cortex
What does actin filament severing proteins break?
changes cytoplasm from a thick, viscous gel-like solution into more aqueous solution as MF depolymerize
allows cytoplasm to flow more towards leading edge
why do myosin family proteins interact with other actin filaments?
to slide MFs in a given direction
What is internal contraction?
retract trailing edge