Overview of the Cytoskeleton from an Evolutionary Perspective
Organisms in the three domains of life depend on protein polymers to form a cytoskeleton that helps to establish their shapes, maintain their mechanical integrity, divide, and, in many cases, move. Eukaryotes have the most complex cytoskeletons, comprising three cytoskeletal polymers-actin filaments, intermediate filaments, and microtubules-acted on by three families of motor proteins (myosin, kinesin, and dynein). Prokaryotes have polymers of proteins homologous to actin and tubulin but no motors, and a few bacteria have a protein related to intermediate filament proteins. Outline 1 Introduction-Overview of cellular functions 2 Structures of the cytoskeletal polymers 3 Assembly of cytoskeletal polymers 4 Overview of the evolution of the cytoskeleton 5 Conclusion