Objective: UPlanSApo 100x oil/1.40	Exposure: 250 ms
Microscope: Olympus DSU/IX81	Gain: 3
Camera: Hamamatsu ImagEM	Interval: 500 ms

Microtubules transport vesicles, organelles, and other molecules throughout the cell. Distribution is regulated by motor proteins that ferry, for instance, secretory vesicles for export from the Golgi apparatus to the plasma membrane. Mitochondria are transported back and forth through the cytoplasm by microtubules, while nerve cells use them to translocate vesicles containing neurotransmitters along their axon tips. Motor proteins "burn" adenosine triphosphate (ATP) to fuel the transformation and travel along the microtubules. By altering their three-dimensional conformation, motor proteins move along the microtubule filament by releasing one portion of the filament and gripping another site farther along the tubule. The digital video above illustrates the tracking of microtubule +TIPs (plus end tracking proteins) in human cervical carcinoma (HeLa line) epithelial cells labeled with a chimera of EB3 fused to mEGFP.