Muscle Contraction Three types of muscles, skeletal, cardiac and smooth, convert metabolic energy to mechanical force and work for myriad functions in the organism. The wide impact of understanding the molecular mechanism and control of muscle contraction in cell biology should be emphasized. The molecular mechanism of muscle contraction is similar to that of cellular and organelle motility which are prerequisites for normal cell development and function.
Contractility is also a model for biological energy transduction and enzymology in general.
The relationship between the amino-acid sequence, structural biology and functional output of motor proteins and contractile proteins are being studied intensively in many PMI labs. As with non-muscle motility, the general paradigm cells use for generating motion is a motor protein sliding along a linear filamentous track. This architecture was first discovered in muscle cells because these elegant machines express and assemble concentrated and highly periodic interdigitating arrays of myosin and actin filaments that are particularly amenable to structural, mechanical and biochemical studies. The filaments do not change length when the muscle contracts, but they slide relative to each other using energy liberated by hydrolysis of ATP to ADP and phosphate. The relationships between the biochemical steps of ATP hydrolysis, the mechanical development of force and filament sliding and the molecular structural changes are the major goals of this research.