# TROPOMYOSIN IN MUSCLE REGULATION

> **NIH NIH R01** · BOSTON BIOMEDICAL RESEARCH INSTITUTE · 1988 · $139,129

## Abstract

The long-term objective of this research is to understand the role
of smooth muscle tropomyosin in the regulation of contraction.
Although this role is presently unclear, it is thought that
tropomyosin's end-to-end interaction plays a key part in the
cooperative nature of regulation.  In order to better understand
the molecular basis of this end-to-end interaction, a specific goal
of this proposal is to investigate the source of the large
heterogeneity in gizzard tropomyosin's end-to-end interaction
observed by hydroxylapatite chromatography.  This question will be
addressed by using several techniques including viscosity,
chromatography, electrophoresis, amino acid analysis, and
sedimentation.  A second specific aim is to test the hypothesis
that tropomyosin's end-to-end interaction is responsible for its
cooperative behavior.  This will be accomplished by determining the
effect of gizzard tropomyosin with different end-to-end
interactions on its cooperative binding to actin and its
cooperative regulation of actomyosin ATPase activity.  Caldesmon,
a new smooth muscle protein, imparts a thin filament Ca2+-
sensitivity to regulation which requires tropomyosin.  In order to
understand the mechanism thereby these two proteins work in
concert, another goal of this project is to determine the effect
of tropomyosin, with different end-to-end interactions, on the
binding of caldesmon to the thin filament and correlate this with
caldesmon's regulation of actomyosin ATPase activity.  Finally,
since the direct interaction between tropomyosin and caldesmon may
play a key role in regulation, this grant proposes to investigate
the direct interaction between tropomyosin, with different end-to-
end interactions, and caldesmon with viscosity, spin labels,
fluorescence labels, sedimentation, and chemical cross-linking.

## Key facts

- **NIH application ID:** 3155925
- **Project number:** 5R01AR030917-05
- **Recipient organization:** BOSTON BIOMEDICAL RESEARCH INSTITUTE
- **Principal Investigator:** Philip Graceffa
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1988
- **Award amount:** $139,129
- **Award type:** 5
- **Project period:** 1982-04-01 → 1992-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3155925

## Citation

> US National Institutes of Health, RePORTER application 3155925, TROPOMYOSIN IN MUSCLE REGULATION (5R01AR030917-05). Retrieved via MORVS 2026-10-24 from https://api.morvs.ai/grant/nih/3155925. Licensed CC0.

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