Structural Plasticity in Actin and Tubulin Polymer Dynamics
Hao Yuan Kueh1,2,* and
Timothy J. Mitchison1,
Actin filaments and microtubules polymerize and depolymerize
by adding and removing subunits at polymer ends, and these dynamics
drive cytoplasmic organization, cell division, and cell motility.
Since Wegner proposed the treadmilling theory for actin in 1976,
it has largely been assumed that the chemical state of the bound
nucleotide determines the rates of subunit addition and removal.
This chemical kinetics view is difficult to reconcile with observations
revealing multiple structural states of the polymer that influence
polymerization dynamics but that are not strictly coupled to
the bound nucleotide state. We refer to these phenomena as "structural
plasticity" and discuss emerging evidence that they play a central
role in polymer dynamics and function.
2 Graduate Program in Biophysics, Harvard University, Cambridge, MA 02139, USA.
* Present address: Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
To whom correspondence should be addressed. E-mail: timothy_mitchison{at}hms.harvard.edu
