# CRYSTALLOGRAPHY OF MUSCLE REGULATORY PROTEINS

> **NIH NIH R01** · RICE UNIVERSITY · 1990 · $95,056

## Abstract

Muscle contraction is switched "on" and "off" in response to external
chemical or electrical signals.  Within each muscle cell activation is
controlled by calcium ions and regulatory proteins:  at high levels of
calcium the muscle is "on", at lower levels the muscle is "off".  This
calcium switch consists of the proteins tropomyosin and troponin.  Using
X-ray crystallography together with electron microscopy I propose to
determine the detailed three-dimensional structure of tropomyosin,
visualize its interactions with troponin in the crystal lattice, and
prepare crystals of troponin and/or its subfragments for high resolution
structure determination.  This information will allow us to better
understand how these proteins control contraction.

Motions of tropomyosin have been postulated to play a critical role in the
regulatory process.  The flexibility of tropomyosin in the crystals will be
examined by analyzing the diffuse X-ray scattering in conjunction with
crystallographic studies at various temperatures.  These results will allow
us to determine the kinds of motions and conformations which tropomyosin
can adopt during the regulatory process.

Although tropomyosin was first discovered in muscle cells, we have recently
recognized that this protein plays an important role in the cytoskeleton of
many cells.  Moreover, tropomyosin-like proteins have been found at the
surface of certain pathogenic bacteria, and appear to be critical factors
in determining their virulence.  Attempts will be made to characterize the
molecular structure of one of these proteins from streptococcal bacteria.
Knowledge of how this "M protein" works could be significant in developing
ways to control streptococcal diseases.

## Key facts

- **NIH application ID:** 3156396
- **Project number:** 5R01AR032764-07
- **Recipient organization:** RICE UNIVERSITY
- **SAM.gov UEI:** K51LECU1G8N3
- **Principal Investigator:** GEORGE NEAL PHILLIPS
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1990
- **Award amount:** $95,056
- **Award type:** 5
- **Project period:** 1984-04-01 → 1992-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3156396

## Citation

> US National Institutes of Health, RePORTER application 3156396, CRYSTALLOGRAPHY OF MUSCLE REGULATORY PROTEINS (5R01AR032764-07). Retrieved via MORVS 2026-10-24 from https://api.morvs.ai/grant/nih/3156396. Licensed CC0.

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