54 Chapter 2. What’s inside cells[[Student version, December 8, 2002]]
Figure 2.26: (Fluorescence optical micrograph.) Experimental demonstration that kinesin and microtubules are
found in the same places within cells. This cell has been doubly labeled with fluorescent antibodies labeling both
kinesin(yellow)and tubulin(green). The kinesin, attached to transport vesicles, is mostly associated with the
microtubule network, as seen from the orange color where fluorescence from the two kinds of antibodies overlap.
[Digital image kindly supplied by S. T. Brady; see (Brady & Pfister, 1991).] [Copyrighted figure; permission pending.]
Figure 2.27:(Video photomicrograph frames.) Motility assay of the fluorescently labeled molecular motor C351, a
single-headed member of the kinesin family. A solution of C351 with concentration between 1–10pMwaswashed over
aset of microtubules fixed to a glass slide. The microtubules were also fluorescently labeled; one of them is shown
here (green). The motors (red) attached to the microtubule, moved along it for several seconds, then detached and
wanderedaway. Twoindividual motors have been chosen for study; their succesive locations are marked by triangles
and arrows respectively. Generally the motors moved strictly in one direction, but backward stepping was also
observed (triangles), in contrast to ordinary, two-headed kinesin. [From (Okada & Hirokawa, 1999).] [Copyrighted
figure; permission pending.]