Using three-dimensional cryoelectron microscopy, the binding positions of tRNA and elongation factors EF-Gr and EF-Tu (the latter complexed with aminoacyl tRNA and GTP) on the ribosome were determined in previous studies, On the basis of these studies, the dynamical events that take place in the course of the elongation cycle of protein synthesis have been animated. The resulting 3-min movie is accessible on the website of this journal (http://www.idealibrary.com). The following article provides a brief annotation of those frames of the movie for which experimental support is available.