Microfilaments generate force through assembly of G-actin into F-actin (Globular monomer to filamentous polymer)

Features:

End on end assembly of monomers
F-actin adopts a tight helical structure
Repeating unit (complete helical turn) = 14 subunits (37nm long, 7nm diameter)

G-actin

Ubiquitous in all eukaryotes and highly conserved
Multiple isoforms= differ in sequence,function, tissue specificity but same general structure: Globular protein, 2 lobes separated by cleft, each lope has 2 domains and hinge between domains I and III
Hinge allows 2 lobes to move relative to one another and form the nucleotide binding cleft (nucleotide= ADP or ATP)
Nucleotide binding is required for G-actin stability
ATP- or ADP-bound G-actin are identical structures except for subdomain 2 (important treadmilling)
G-actin monomers have polarity (important for end on end stacking)

	Created by Chloe Cavarretta over 7 years ago

Lectures 1-3 of Cell Biology