Muscle Proteome Dynamics.

Skeletal muscle demonstrates remarkable malleability and can alter in metabolic and contractile properties in response to changes in environmental stimuli, in particular contractile work. The muscle proteome defines muscle by dictating its functional characteristics and coordinating its adaptive responses to external stimuli. The dynamic aspects of the proteome have not yet been widely studied and most current proteomic data chart changes to the abundance profile or post-translational state of proteins during the process of adaptation. Nevertheless, the proteome is a dynamic entity. Proteins exist in a constant cycle of renewal, known as protein turnover, which is essential to maintain the quality of the proteome and to facilitate adaptation. Adaptation is only possible because proteins exist in a flux of synthesis and degradation. Furthermore, synthesis and degradation are each highly regulated processes and, in themselves, change in response to stimuli. Isotope tracers are required to study proteome dynamics, and stable isotopes, such as deuterium that impart a mass tag to newly synthesised proteins, are ideally suited to mass spectrometry-based proteomic analyses. New proteomic methods are now emerging that simultaneously measure the abundance and synthesis rate of large numbers of individual proteins. This chapter provides an overview of developments in this field.