How can the products of a single gene be localized to more than one intracellular compartment?

Protein-targeting sequences are specific for each intracellular compartment, so that most proteins are found at only one location within the eukaryotic cell. Increasingly, however, examples are being found of proteins that occur and function in more than one cellular compartment. In some cases, the multicompartmentalized isoforms are encoded by the same gene. Several mechanisms have evolved to enable such genes to encode and differentially express multiple types of topogenic information. These mechanisms include alternative forms of transcription initiation, translation initiation, splicing and post-translational modification.