Journal of Neuroscience, Vol 12, 750-761, Copyright © 1992 by Society for Neuroscience
An actin-associated protein present in the microtubule organizing center and the growth cones of PC-12 cells
EL Bearer
Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0448.
The pathfinding ability of the growth cone depends upon the integrity of a
dynamic actin filament network. However, although a number of actin-binding
proteins have been found in growth cones, it is not known how these
proteins come to be concentrated there or how they might interact to
produce these important actin filaments. In this report, an
actin-associated protein recognized by the monoclonal antibody 2E4 is
demonstrated to be present in PC-12 cells. In undifferentiated cells, this
protein is present in an apparently inactive state in a perinuclear
location that corresponds to that of the microtubule organizing center and
not of the Golgi apparatus. Conversely, after NGF- induced differentiation,
the antigen is found enriched in the neurite and growth cone and disappears
from the perinuclear position. This disappearance is directly proportional
to the length of the neurite. The antigen-antibody complex binds the ends
of actin filaments in vitro in an ATP-sensitive manner, and the antibody
stains the outermost edge of the actin filament ruffle in the leading edge
of migrating fibroblasts. Hence, it is possibly involved in the
membrane-associated polymerization of actin filaments such as that observed
in growth cones.
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