Abstract
The recent application of digital imaging technologies to the analysis of video images from a DIC (differential interference contrast) light microscope has given 1-2 nm precision for the measurement of movements of submicron particles at 30 Hz. [Gelles et al., Nature 331(1988)450]. This technique has been applied to the study of the movements of 1) motor proteins (kinesin and cytoplasmic dynein) on microtubules (MTs) and 2) membrane glycoproteins in cellular plasma membranes. In both cases the nanometer measurements have provided important new insights into the molecular mechanisms which govern those biological movements.