ABSTRACT
I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 741 II. Polymerization Forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 742 III. Depolymerization Forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 744 IV. Examples of Cellular Polymerization Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 746 V. Other Mechanisms of Force Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 747 VI. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 749 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 750
I. INTRODUCTION
Polymers perform many tasks in living cells. We discuss their roles in generating mechanical forces that drive important cellular motions. These can be classified into three general categories:
In this chapter we will focus on categories 1 and 2. Polymer motors do not operate in a cyclic fashion like other protein motors that cycle through a number of conformational steps and eventually reset themselves to their initial configuration. Rather they are “one-shot” engines that, after assembly, are disassembled. Nevertheless, these specialized motors play an important role in many cellular processes.
