Produced by the soil bacterium Streptomyces griseus, cycloheximide binds the exit (E) site of the eukaryotic 60S ribosomal subunit and halts the translocation of tRNA and mRNA during translational elongation without inhibiting prokaryotic 70S ribosomes.
In a "cycloheximide chase" assay, cells are treated with cycloheximide to arrest new protein synthesis and lysed at serial timepoints for Western blotting to measure the intracellular degradation half-life of short-lived proteins such as p53 or c-Myc.
In neuropharmacology and gene-regulation experiments, pretreating cells with cycloheximide distinguishes immediate-early genes (whose mRNA is transcribed without de novo protein synthesis) from secondary downstream transcriptional targets.