ABSTRACT
Cell metabolism involves a collection of biochemical reactions to process carbohydrates, amino acids, and lipids to generate energy and to synthesize essential cellular building blocks. Catalyzed by metabolic enzymes, each reaction transforms a substrate, be it the initial nutrient or an intermediate metabolite, into a product for the subsequent reaction. Together, these reactions constitute elaborate metabolic pathways for particular fuels, such as glycolysis to convert glucose into pyruvate, as well as β-oxidation to break down fatty acids. From a labyrinthine ensemble of metabolic pathways, cells derive energy and macromolecules to perform diverse physiological functions that encompass circadian rhythm (Bass and Takahashi 2010; Asher and Schibler 2011), cell proliferation (Buchakjian and Kornbluth 2010; Lunt and Vander Heiden 2011), cell survival (Vaughn and Deshmukh 2008; Yi et al. 2011), and gene regulation (Zheng et al. 2003; Wellen et al. 2009). Metabolism thus provides crucial housekeeping functions for all cells.
