Eukaryotic Gene Expression Problem Set

Problem 4: Self-catalytic RNAs

Tutorial to help answer the question

RNAs that catalyze biological reactions, such as self-splicing introns, are known as:


The term "ribozyme" was originally suggested by Thomas R. Cech, Nobel Prize winning biochemist, who first discovered this class of RNA molecules. A ribozyme is an RNA molecule that can catalyze a biochemical reaction. Prior to the discovery of ribozymes, it was generally assumed that protein enzymes were the only class of biological catalysts. Cech's discovery was truly revolutionary in upsetting this dogma.

The first ribozymes discovered were introns that could catalyze their own splicing, i.e. a special type of intron within a pre-RNA molecule was found to catalyze all steps needed for intron removal and joining of the exons together at the biologically correct site. Ribozymes with other types of biological activity have since been discovered. One intriguing potential ribozyme is the peptidyl transferase activity of the ribosome. Many believe that peptide bond formation is catalyzed by the 23S ribosomal RNA, a potential ribozyme, rather than ribosomal proteins.

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Monday, October 27, 1997
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