[Molecular diversity of enzymes by transcriptional and translational mechanism]

This article discusses a molecular basis for isozyme production. Molecular diversity of enzymes is often created by genetic mechanisms, especially at the level of transcription and translation. First, transcription from several promoters in the same gene and alternative splicing make several transcripts which vary in length and the context. Isozymes are produced if the translation initiating codons are located in the in-frame position. Additional regions usually have the information of the targeting signal to the cellular compartment and/or the regulatory mechanism of enzyme activity. Second, the regulation of the translational initiation is another important step to make isozymes. Two mechanisms, that is, cap-dependent and internal ribosome binding, are currently recognized for the translational initiation.