580 Chapter 18 • The Genetic Basis of Development proteins hydrolyze ATP for energy that is utilized to propel movement along a microtubule. For example, a protein called kinesin is able to move in a ± to ² direction along microtubules, carrying cargos such as vesicles from the center of the cell to its periphery (Figure 18-5a and b). The motor—the part of the kinesin protein that directly interacts with the micro-tubule rod—is contained in the globular heads of the protein (Figure 18-5c). The tail of kinesin is thought to be where the cargo is attached. These cargos might be individual molecules, organelles, or other subcellular particles to be towed from one part of the cell to an-other. (Other motors exist that travel in the ² to ± direction on microtubules, and still other motors can travel in each of the two directions on actin microﬁla-ments.) What is the value of having multiple indepen-dent trafﬁcking systems? A part of the answer is division of labor. Different cell components must be moved to
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This note was uploaded on 01/10/2011 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.