REGULATION OF MUSCLE MITOCHONDRIAL DESIGN

Mitochondria are responsible for the generation of ATP to fuel muscle contraction, Hypermetabolic stresses imposed upon muscles can lead to mitochondrial proliferation, but the resulting mitochondria greatly re semble their progenitors, During the mitochondrial biogenesis that acc ompanies phenotypic adaptation, the stoichiometric relationships betwe en functional elements are preserved through shared sensitivities of r espiratory genes to specific transcription factors, Although the prope rties of muscle mitochondria are generally thought to be highly conser ved across species, there are many examples of mitochondrial differenc es between muscle types, species and developmental states and even wit hin single cells, In this review, we discuss (1) the nature and regula tion of gene families that allow coordinated expression of genes for m itochondrial products and (2) the regulatory mechanisms by which mitoc hondrial differences can arise over physiological and evolutionary tim e.