# SMOOTH MUSCLE AND NONMUSCLE CALDESMON

> **NIH NIH R01** · BOSTON BIOMEDICAL RESEARCH INSTITUTE · 1993 · $174,884

## Abstract

Smooth muscle, which lines the periphery of hollow organs, contracts to
change the shape of the organ or maintains tension to fix the shape.  An
understanding of the regulation of smooth muscle contraction could help
to form the basis for understanding a number of diseases, including
hypertension in the vascular system and asthma in the airways of the
lung.  Smooth muscle contraction is primarily regulated by
Ca2+-calmodulin dependent phosphorylation of myosin in the thick
filament.  Evidence is accumulating for an additional regulatory
mechanism associated with the actin thin filament involving caldesmon, a
long, thin, actin-binding protein, and tropomyosin.  A much shorter
isoform of caldesmon is also found in a wide range of non-muscle tissue
including brain, liver, kidney, and platelets.  Non-muscle caldesmon is
thought to play a role in regulating the shape and motility of cells.
However very little is known about its function.  Thus the long range
goal of this project is to uncover the molecular mechanisms whereby
caldesmon, in concert with tropomyosin, regulates smooth muscle
contraction and non-muscle motility and shape.  The immediate objective
is to map the arrangement of smooth muscle and non-muscle caldesmon, and
tropomyosin, on the actin filament.  The results of such studies will be
correlated with actomyosin ATPase activity, the test tube analogue of
contraction, in order to connect structure with function.  These aims
will be pursued with reconstituted and native thin filaments and intact
myofibrils.  The project will make use of spectroscopic and cross-linking
probes specifically attached to particular domains of caldesmon and
tropomyosin in order to probe these regions of the proteins in their
interaction with each other and other contractile proteins.  In
particular, spin labels, fluorescence labels, photocross-linkers, and
disulfide cross-linkers will be used.  Electron microscopy and the
hydrodynamic techniques of viscosity and analytical ultracentrifugation
will also be employed.

## Key facts

- **NIH application ID:** 3155924
- **Project number:** 2R01AR030917-09A1
- **Recipient organization:** BOSTON BIOMEDICAL RESEARCH INSTITUTE
- **Principal Investigator:** Philip Graceffa
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1993
- **Award amount:** $174,884
- **Award type:** 2
- **Project period:** 1982-04-01 → 1997-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3155924

## Citation

> US National Institutes of Health, RePORTER application 3155924, SMOOTH MUSCLE AND NONMUSCLE CALDESMON (2R01AR030917-09A1). Retrieved via MORVS 2026-10-24 from https://api.morvs.ai/grant/nih/3155924. Licensed CC0.

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