Isoform sorting and the creation of intracellular compartments

The generation of isoforms via gene duplication and alternative splicing ha s been a valuable evolutionary tool for the creation of biological diversit y. In addition to the formation of molecules with related but different fun ctional characteristics, it is now apparent that isoforms can be segregated into different intracellular sites within the same cell. Sorting has been observed in a wide range of genes, including those encoding structural mole cules, receptors, channels, enzymes, and signaling molecules. This results in the creation of intracellular compartments that (a) can be independently controlled and (b) have different functional properties. The sorting mecha nisms are likely to operate at the level of both proteins and mRNAs. Isofor m sorting may be an important consequence of the evolution of isoforms and is likely to have contributed to the diversity of functional properties wit hin groups of isoforms.