Molecular motors Motor proteins

Natural molecular motors (motor proteins) are intriguing, both as efficient products of evolution and as power sonrces for nanotechnology (7). Some representative rotary and linear motor proteins are subjects of this chapter. Not discussed here are a wide range of additional proteins in which linear motion is coupled with enzyme activity, or which perform physical work. Examples are RNA polymerase and DNA topoisomerase, respectively. 

Wilkens S (2005) Rotary molecular motors. Adv Protein Chem 71 345-382. 

Protein dynamics—the action of enzymes and molecular motors—provides the key to understanding the biochemistry of this cheetah and the grasses through which it runs. (Frank Lane/Parfitt/Tony Stone Images)... 

Motor proteins, also known as molecular motors, use chemical energy (ATP) to orchestrate all these movements, transforming ATP energy into the mechanical energy of motion. In all cases, ATP hydrolysis is presumed to drive and... 

Even though dynein, kinesin, and myosin serve similar ATPase-dependent chemomechanical functions and have structural similarities, they do not appear to be related to each other in molecular terms. Their similarity lies in the overall shape of the molecule, which is composed of a pair of globular heads that bind microtubules and a fan-shaped tail piece (not present in myosin) that is suspected to carry the attachment site for membranous vesicles and other cytoplasmic components transported by MT. The cytoplasmic and axonemal dyneins are similar in structure (Hirokawa et al., 1989 Holzbaur and Vallee, 1994). Current studies on mutant phenotypes are likely to lead to a better understanding of the cellular roles of molecular motor proteins and their mechanisms of action (Endow and Titus, 1992). 

Coming, P.A. (2002). Thermoeconomics beyond the second law. J. Bioeconom., 4, 57-88 Everett, D.H. (1959). An Introduction to Chemical Thermodynamics. Longmans, London Kinosita, K., Yasuda, R., Noji, H. and Adachi, K. (2000). A rotary molecular motor that can work at near 100% efficiency. Philos. Trans. Act. Royal Soc. London B, 355, 473—489. See also Proc. Biochem. Soc. (2005) Meeting Mechanics of Bioenergetic Membrane Proteins Structures and... 

Although many motor proteins are found in nervous tissue, there are few instances in which we hilly understand their cellular functions. The proliferation of different motor molecules and the existence of numerous isoforms raises the possibility that some physiological activities require multiple motors. There may be cases in which motors serve a redundant role to ensure that the physiological activity is maintained in the event of a loss of one motor protein. Finally, the existence of so many different types of motor molecule suggests that novel physiological activities requiring molecular motors may be as yet unrecognized. 

Hirokawa, N. and Takemura, R. Biochemical and molecular characterization of diseases linked to motor proteins. Trends Biochem. Sci. 28 558-565, 2003. 

The following are recent reviews dealing with this ATP-dependent motor protein that is responsible for vesicle locomotion along microtubules in eukaryotes. See Force Effects on Molecular Motors... 

Many experiments have been carried out by using this setup the stretching of single DNA molecules, the unfolding of RNA molecules or proteins, and the translocation of molecular motors (Fig. 2). Here we focus our attention on force experiments where mechanical work can be exerted on the molecule and nonequilibrium fluctuations are measured. The most successful studies along this line of research are the stretching of small domain molecules such as RNA [83] or protein motifs [84]. Small RNA domains consist of a few tens of nucleotides folded into a secondary structure that is further stabilized by tertiary interactions. Because an RNA molecule is too small to be manipulated with micron-sized beads, it has to be inserted between molecular handles. These act as polymer spacers that avoid nonspecific interactions between the bead and the molecule as well as the contact between the two beads. 

Protein Interactions Modulated by Chemical Energy Actin, Myosin, and Molecular Motors 182... 

The NBDs of all ABC proteins are similar in sequence and presumably in three-dimensional structure they are the conserved molecular motor that can be coupled to a wide variety of pumps and channels. When coupled with... 

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