Identification of a noncatalytic domain in AMP deaminase that influences binding to myosin

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Abstract
AMP deaminase (AMP-D) plays a critical role in energy metabolism in skeletal muscle. Prior studies have demonstrated AMP-D binds to myosin heavy chain in vitro, and it decorates the end of the A band in the myofibril. The present study presents evidence that proteolytic removal of 14 kilodaltons, presumably from the carboxy terminus, of the native 80K peptide does not eliminate catalytic activity but this deletion has a pronounced influence on binding of AMP-D to myosin in the presence of ATP. Comparison of the sequence of the rat skeletal muscle form of AMP-D to that of yeast AMP-D demonstrates conservation of an ATP binding site in the carboxy-terminal domain of the rat protein. These results provide a mechanism for regulating binding of AMP-D to myosin heavy chain in response to changes in ATP concentration and suggest a potential function for AMP-D/myosin complex formation in myocytes.