Visualization and assessment of physical and chemical interactions among smooth muscle proteins

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This research program introduces an innovative technique of studying interactions of proteins by combining protein biochemistry and molecular imaging at every step of the interaction. This technique is crucial for understanding protein interactions that critically depends on the structure of the protein aggregate (e.g., when the structure of the aggregate is a factor determining the chemical properties of the aggregate). A good application of this technique is in the study of the interaction of myosin and actin (major proteins responsible for generating force and movement in muscle cells) in muscle contraction. Both myosin and actin exist in muscle cells in filamentous forms due to polymerization of the proteins and it is the interaction of filamentous myosin and filamentous actin that occurs in the cell and not the interaction between individual myosin and actin molecules. It is therefore crucial to visualize the elements involved in the reaction. Another focus of this research program is aimed at elucidating the basic mechanism of contraction in smooth muscle (the type of muscle found in hollow organs like stomach, urinary bladder, blood vessels and airways that controls vital organ functions). Compared to skeletal or heart muscles, we know very little about how smooth muscle works. We propose to construct the basic contractile unit in smooth muscle using purified smooth muscle contractile proteins as building blocks. This will allow us to understand the molecular constituents of the contractile unit and how it works. The research program will have great impacts on both our understanding of basic cell physiology of smooth muscle and the development of a novel technique that can be used in many fields of research that seek to understand the nature of interaction between nano-particles or molecules, especially when the structure (or conformation) of the particle or molecular aggregates is an important consideration.