Katalin Ajtai

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Ventricular myosin (βMys) is the motor protein in cardiac muscle generating force using ATP hydrolysis free energy to translate actin. In the cardiac muscle sarcomere, myosin and actin filaments interact cyclically and undergo rapid relative translation facilitated by the low duty cycle motor. It contrasts with high duty cycle processive myosins for which(More)
Myosin in muscle transduces ATP free energy into the mechanical work of moving actin. It has a motor domain transducer containing ATP and actin binding sites, and, mechanical elements coupling motor impulse to the myosin filament backbone providing transduction/mechanical-coupling. The mechanical coupler is a lever-arm stabilized by bound essential and(More)
Myosin 2 is the molecular motor in muscle. It binds actin and executes a power stroke by rotating its lever arm through an angle of approximately 70 degrees to translate actin against resistive force. Myosin 2 has evolved to function optimally under crowded conditions where rates and equilibria of macromolecular reactions undergo major shifts relative to(More)
Myosin cross-bridge subfragment 1 (S1) is the ATP catalyzing motor protein in muscle. It consists of three domains that catalyze ATP and bind actin (catalytic), conduct energy transduction (converter), and transport the load (lever arm). Force development during contraction is thought to result from rotary lever arm movement with the cross-bridge attached(More)
It is widely conjectured that muscle shortens because portions of myosin molecules (the "cross-bridges") impel the actin filament to which they transiently attach and that the impulses result from rotation of the cross-bridges. Crystallography indicates that a cross-bridge is articulated-consisting of a globular catalytic/actin-binding domain and a long(More)
Muscle myosins transduce ATP free energy into actin displacement to power contraction. In vivo, myosin side chains are modified post-translationally under native conditions, potentially impacting function. Single myosin detection provides the 'bottom-up' myosin characterization probing basic mechanisms without ambiguities inherent to ensemble observation.(More)
Smooth muscle myosin gene products include two isoforms, SMA and SMB, differing by a 7-residue peptide in loop 1 (i7) at the myosin active site where ATP is hydrolyzed. Using chicken isoforms, previous work indicated that the i7 deletion in SMA prolongs strong actin binding by inhibiting active site ingress and egress of nucleotide when compared to i7(More)
BACKGROUND Myosin performs ATP free energy transduction into mechanical work in the motor domain of the myosin heavy chain (MHC). Energy transduction is the definitive systemic feature of the myosin motor performed by coordinating in a time ordered sequence: ATP hydrolysis at the active site, actin affinity modulation at the actin binding site, and the(More)
Myosin subfragment 1 (S1) is the ATP catalyzing motor protein in muscle. It consists of three domains that catalyze ATP and bind actin (catalytic), conduct energy transduction (converter), and transport the load (lever arm). These domains interface in two places identified as interface I, containing the reactive thiol (SH1) and ATP-sensitive tryptophan(More)