# THE NATURE OF MUSCLE FIBER DENSITY

> **NIH NIH R01** · DUKE UNIVERSITY · 1990 · $191,396

## Abstract

In skeletal muscle a large number of contractile protein isoforms
are expressed. Our goal is to understand how the expression of
these different isoforms is controlled and how they affect fiber
physiology.  During the first six years of this award, we
established the biochemical and physiological foundation for these
studies.  Applying high resolution SDS-PAGE and HPLC, monoclonal
antibodies and aminoacid sequence analyses in combination with
physiological studies we:  1) identified three major programs of
troponin-tropomyosin expression in fast skeletal muscle fibers 2)
found that the coexpression of these programs in different ratios
in muscle fibers results in a molecular continuum of fast fibers
and 3) demonstrated that this molecular continuum determines the
continuum of physiological and ultrastructural properties of fast
fibers.  These observations led us to develop new ways of thinking
about contractile protein, and this in turn has resulted in a shift
in our research emphasis to the cellular mechanisms that regulate
coexpression of different thin filament programs we have defined.
In these studies, we will establish the basis for a molecular
understanding of the ways the different TnT-Tm programs control the
physiological response to calcium; and using a variety of
approaches, including microinjection pulse labelling oligo probes
and eukaryotic expression vectors, will identify the mechanisms
that control tropomyosin transcription and translation and
coordinate its expression with that ofthe different alternatively
spliced troponin T isoforms.

## Key facts

- **NIH application ID:** 3158069
- **Project number:** 5R01AR037344-08
- **Recipient organization:** DUKE UNIVERSITY
- **SAM.gov UEI:** TP7EK8DZV6N5
- **Principal Investigator:** FREDERICK H SCHACHAT
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1990
- **Award amount:** $191,396
- **Award type:** 5
- **Project period:** 1986-01-01 → 1993-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3158069

## Citation

> US National Institutes of Health, RePORTER application 3158069, THE NATURE OF MUSCLE FIBER DENSITY (5R01AR037344-08). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3158069. Licensed CC0.

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