# MYOFIBRILLAR, STRUCTURE IN STRIATED MUSCLE

> **NIH NIH R01** · DUKE UNIVERSITY · 1987 · $181,490

## Abstract

Myofibril structure of insect flight muscle (IFM) is being studied
by coordinated use of electron microscopy, X-ray diffraction,
quantitative microscopy and biochemical analysis, and emphasis
on the structure and behavior of myosin crossbridges.
Crossbridges are the primary movers in muscle contraction and
most non-muscle motility, and their highly ordered lattice
arrangement in IFM permits averaging methods to extract
crossbridge structure indifferent states which can be related to
different phases of their ratchet-like cycle.  X-ray and optical
diffraction criteria will guide our search for better fixation of
actin and crossbridges by modifying glutaraldehyde with tannic
acid, diamines, and polyethylene-glycol triazine.  Quick-freeze
and freeze-substitution methods will be optimized for thin-
sectioning of stable states like rigor and relaxed before
attempting the study of dynamic structural transitions.  3-D
computer reconstructions from 10-25 nm sections, based on
multiple tilt views and on oblique cross sections, will be
completed for rigor and applied to a group of necleotide-induced
states, to establish definitively the variation in size, shape and
domain alignment of crossbridges.   Computer modelling will
explore how EM structure of actin and crossbridges of rigor can
be reconciled with X-ray intensity modelling.  EM-mechanical
correlation studies of single fibers will characterize two new
crossbridge configurations encountered in glycol-AMPPNP-
induced progression of states, and will explore rigor induction and
tension to examine the length of the power-stroke, strength of
bridge attachment, and effects of crossbridge "slippage".  We
expect to finish coordinated collaborative studies of crossbridge
orientation by EM/X-ray and spin-labelling, and antibody
localization of troponin within the crossbridge lattice.  IN a
different approach, quantitative microscopy (EM and
interference), buoyant density banding in Percoll, and X-ray
diffraction measurement of lattice spacing will be coordinated in
studies of dry mass content of myofilaments and fibrils, to
produce mass distribution profiles of insect and rabbit
sarcomeres, ascertain absolute protein conon in sarcomere cross-
bands, and to resolve an anomalous discrepancy between filament
mass and whole fibril mass.

## Key facts

- **NIH application ID:** 3154804
- **Project number:** 2R01AR014317-16
- **Recipient organization:** DUKE UNIVERSITY
- **SAM.gov UEI:** TP7EK8DZV6N5
- **Principal Investigator:** MICHAEL KAY REEDY
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1987
- **Award amount:** $181,490
- **Award type:** 2
- **Project period:** 1979-05-01 → 1992-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3154804

## Citation

> US National Institutes of Health, RePORTER application 3154804, MYOFIBRILLAR, STRUCTURE IN STRIATED MUSCLE (2R01AR014317-16). Retrieved via MORVS 2026-10-24 from https://api.morvs.ai/grant/nih/3154804. Licensed CC0.

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