BIO315H5 Lecture Notes - Lecture 16: Myosin Light Chain, Endoplasmic Reticulum, Skeletal Muscle
Document Summary
Last class we talked about the different types of cytoskeletal structures: actin, microtubules and intermediate filaments. The arp2/3 complex helps to nucleate actin filament formation from the minus end - needed for nucleation of actin filament to form web like structures. Formin is another protein that facilitates actin nucleation. Formin nucleates the growth of straight, unstretched actin filament - unlike webs formed with. Formins work as dimers that capture 2 actin monomers and bring them to the plus end. Each monomer of that formin dimer interacts with one actin monomer. Formins remain associated with the plus end of the filament, while still allowing binding of new subunits. Formin has unstructured whisker-like regions that help to capture the profilin-actin complex and bring it towards the plus end. Side binding proteins vs. end binding proteins. Tropomyosin - side-binding actin protein, binds to adjacent actin subunits on one protofilament. Through this binding tropomyosin actually stabilizes the filament.
