Richard L Cross, PhD
- Distinguished Professor of Biochemistry and Molecular Biology
- Professor of Microbiology and Immunology
- Professor of Neuroscience and Physiology
Research Programs and Affiliations
- Biochemistry and Molecular Biology
- Biomedical Sciences Program
- Neuroscience and Physiology
- Research Pillars
Education & Fellowships
- Postdoctoral Fellow: University of California at Los Angeles
- PhD: Yale University, 1970
- Bioenergetics, enzymology, structural biology, membrane protein function
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Oxidative Phosphorylation/FoF1-ATP Synthase/Biological Rotary Motors (with Dr. Thomas Duncan)
FoF1-ATP synthases are found embedded in the membranes of mitochondria, chloroplasts and bacteria, and are responsible for the production of most of the cellular ATP required to maintain the living state. To accomplish this critical task, FoF1 must be able to extract energy from a transmembrane electrochemical gradient of protons produced during respiration or photosynthesis. The Fo portion of the synthase is composed of membrane-spanning subunits that catalyze the transport of protons, whereas the F1 portion is an extrinsic complex that contains the catalytic sites for ATP synthesis. The mechanism by which FoF1 is able to achieve efficient, reversible energy coupling between a gradient of protons and the chemical energy stored in ATP has been a major focus of research in biochemistry for many years. The model for energy coupling by FoF1-ATP synthases that has gained the most general support is called the binding change mechanism. According to this model, the ATP synthase functions as a rotary motor driven by a current of protons. Subunit rotation in Fo is required to complete the path for protons being transported down a gradient. The accompanying rotation of subunits in F1 (see figure below) drives the binding of substrates to and the release of ATP from the three catalytic subunits.
The Binding Change Mechanism
A major goal of our research program is to further test and refine this model. For this purpose, we use site-directed mutagenesis, ligand binding measurements, affinity labeling and cross-linking, kinetic analyses, structural studies and single-molecule measurements. We are also interested in the regulation of the synthase by the binding of adenine nucleotides at allosteric and catalytic sites.
Milgrom YM, Cross RL. Rapid hydrolysis of ATP by mitochondrial F1-ATPase correlates with the filling of the second of three catalytic sites. Proc Natl Acad Sci U S A. 2005 Sep 27;102(39):13831-6. Epub 2005 Sep 19.
Cross RL, Müller V. The evolution of A-, F-, and V-type ATP synthases and ATPases: reversals in function and changes in the H+/ATP coupling ratio. FEBS Lett. 2004 Oct 8;576(1-2):1-4. Review.