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The nitroxide spin label (iodoacetamido)proxyl (IPSL) was specifically and rigidly attached to sulfhydryl 1 (SH1) on myosin subfragment 1 (S1). The specificity of this label for SH1 was demonstrated by using a technique where the spin label is localized on the electrophoresis-isolated proteolytic fragments of myosin using electron paramagnetic resonance(More)
Cardiac and skeletal muscle myosins have the central role in contraction transducing ATP free energy into the mechanical work of moving actin. Myosin has a motor domain containing ATP and actin binding sites and a lever-arm that undergoes rotation impelling bound actin. The lever-arm converts torque generated in the motor into the linear displacement known(More)
The labeling of muscle fiber proteins with iodoacetamido)tetramethylrhodamine (IATR) was reinvestigated with the purified 5' or 6' isomers of IATR. Both isomers modify the myosin heavy chain within the 20-kDa fragment of myosin subfragment 1 (S1) but with different rates, and only the 5'-IATR alters K(+)-EDTA- and Ca(2+)-activated ATPases. Absorption(More)
The technique of polarized fluorescence photobleaching recovery (PFPR) has been applied for the first time to investigation of the rotational correlation time of the myosin head in muscle fibers. This is a novel application of PFPR because it is the first time PFPR has been applied to a sample which is not cylindrically symmetric about the optical axis.(More)
Myosin powers contraction in heart and skeletal muscle and is a leading target for mutations implicated in inheritable muscle diseases. During contraction, myosin transduces ATP free energy into the work of muscle shortening against resisting force. Muscle shortening involves relative sliding of myosin and actin filaments. Skeletal actin filaments were(More)
Myosin is the molecular motor in muscle-binding actin and executing a power stroke by rotating its lever arm through an angle of approximately 70 degrees to translate actin against resistive force. A green fluorescent protein (GFP)-tagged human cardiac myosin regulatory light chain (HCRLC) was constructed to study in situ lever arm orientation one molecule(More)
Specific phosphorylation of the human ventricular cardiac myosin regulatory light chain (MYL2) modifies the protein at S15. This modification affects MYL2 secondary structure and modulates the Ca(2+) sensitivity of contraction in cardiac tissue. Smooth muscle myosin light chain kinase (smMLCK) is a ubiquitous kinase prevalent in uterus and present in other(More)
We investigated the molecular function of PDLIM4 in prostate cancer cells. PDLIM4 mRNA and protein-expression levels were reduced in LNCaP, LAPC4, DU145, CWR22, and PC3 prostate cancer cells. The re-expression of PDLIM4 in prostate cancer cells has significantly reduced the cell growth and clonogenicity with G1 phase of cell-cycle arrest. We have shown the(More)
Myosin motors transduce ATP free energy into mechanical work. Transduction models allocate specific functions to motor structural domains beginning with ATP hydrolysis in the active site and ending in a lever-arm rotating power-stroke. Myosin light chains, regulatory (RLC) and essential (ELC), bind IQ-domains on the lever-arm and track its movement. Strong(More)
Fluorescence detection of single molecules provides a means to investigate protein dynamics minus ambiguities introduced by ensemble averages of unsynchronized protein movement or of protein movement mimicking a local symmetry. For proteins in a biological assembly, taking advantage of the single molecule approach could require single protein isolation from(More)