Abstract: | The effect of ribosome-inactivating proteins (RIPs), eithersingle-chain or toxins, was studied on plant ribosomes. RIPsdid not affect ribosomes from their own plants, while inhibitingto a variable extent protein synthesis by heterologous plantribosomes. Ricin stimulated and PAPS inhibited the growthof carrot cells in culture. Key words: Plant ribosomes, Ribosome-inactivating proteins, Protein synthesis, Ribosome specificity, Plant cell cultures |