RNA splicing: Advantages of parallel processing

Parallel and sequential modes of RNA processing are systematically compared by an analysis of the relevant kinetic reaction schemes. The parallel mode is shown to be superior in the sense that it allows molecules to be processed with larger numbers of introns, smaller losses of immature intermediates, and shorter processing times. It also is more sensitive to variations in the rate constants for individual splice-reactions, and hence more amenable to evolutionary refinements. Quantitatively, the parallel mode agrees well with published experimental data.