Forum 11/21/2002

“Three-dimensional structure of the ADP and rigor states of and -cardiac S1 bound to F-actin”

Kimberly Littlefield, Guest Scientist – Department of Cell Biology, The Scripps Research Institute, La Jolla, CA

The structural transitions that occur during the myosin ATPase cycle are complete after phosphate release in skeletal myosin II.  However, ADP release mediates an additional swing of the light chain binding domain (LCBD) in other class II myosins such as smooth and non-muscle myosin IIB.  We are investigating the structural characteristics of the LCBD of уnand -cardiac S1 bound to actin in the ADP and rigor (nucleotide-free) states using cryo-electron microscopy and helical image analysis.  Our results suggest that a strain-dependent mechanism of ADP release may account for the unique physiology of cardiac myosin.