# INTERACTION OF MYOSIN WITH ACTIN

> **NIH NIH R01** · UNIVERSITY OF ALABAMA AT BIRMINGHAM · 1991 · $179,346

## Abstract

Cyclic association and dissociation of cross-bridges formed between
myosin molecules in the thick filament and actin molecules in the thin
filament are coupled to ATP hydrolysis.  The coupled cycle can lead to
sliding of the filaments thus resulting in generation of force and
production of work.  An understanding of the mechanism by which chemical
free energy released from ATP hydrolysis is converted to mechanical work
(contraction) requires detailed knowledge of molecular interactions that
are involved in the sliding motions.  Evidence points to the presence of
an energy transduction "loop" within the subfragment l(Sl) region of
myosin.  Intersite communication between biologically relevant sites
(actin-binding, ATP) within this loop is an important feature of energy
transduction in muscle.
     The first part of the proposed work addresses the association and
dissociation kinetics of actin with fluorescently-labeled Sl.  We will
examine the kinetics of these reactions with both unregulated and
regulated actin filaments by using stopped-flow and temperature-jump
relaxation fluorometry.  The second project is designed to understand the
relationship between intersite communication and the dynamic properties
of the heavy chain of Sl.  We will determine molecular distances by
fluorescence resonance energy transfer (FRET) and use these distances to
elucidate structural changes that occur in Sl and the complex formed
between actin and Sl resulting from muscle activation..  Intramolecularly
crosslinked Sl and intermolecularly crosslinked proteins will be used for
these studies.  The changes in FRET induced by biologically relevant
perturbations will be kinetically resolved in rapid kinetic experiments.
Both kinetic and spectroscopic information will be incorporated into
contractile models.  Synthetic peptides will be used as models to study
the flexibility of a short segment of Sl heavy chain.  They will be
studied by NMR, fluorescence and computer simulation.  Finally, we will
obtain collaboratively mutant nSl proteins that have specific sequence
alteration for structure/function studies.

## Key facts

- **NIH application ID:** 3156006
- **Project number:** 2R01AR031239-06A2
- **Recipient organization:** UNIVERSITY OF ALABAMA AT BIRMINGHAM
- **SAM.gov UEI:** YND4PLMC9AN7
- **Principal Investigator:** HERBERT C CHEUNG
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1991
- **Award amount:** $179,346
- **Award type:** 2
- **Project period:** 1991-06-07 → 1995-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3156006

## Citation

> US National Institutes of Health, RePORTER application 3156006, INTERACTION OF MYOSIN WITH ACTIN (2R01AR031239-06A2). Retrieved via MORVS 2026-10-24 from https://api.morvs.ai/grant/nih/3156006. Licensed CC0.

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