AJP - Endocrinology and Metabolism, Vol 240, Issue 5 493-E498, Copyright © 1981 by American Physiological Society
Immunofluorescent localization of a Ca2+-dependent neutral protease in hamster muscle
R. Barth and J. S. Elce
A Ca2+-dependent neutral thiol protease is widely distributed in mammalian
tissues and has been implicated in muscle protein turnover. As a first step
to understanding the physiological function of this enzyme, its cellular
and subcellular localization has been studied in hamster cardiac and
skeletal muscle by means of indirect immunofluorescence. The results showed
that the Ca2+-dependent protease is located either at the plasma membrane
or in the connective tissue matrix that surrounds the muscle cels. The
uniform distribution along membranes and around capillaries indicated that
the protease is not confined to connective tissue cells. This evidence,
together with the Ca2+-dependence of the enzyme, suggests a distribution
throughout the extracellular connective tissue of the muscle. In this
position, it would seem unlikely that the enzyme could participate in
protein turnover within muscle cells in normal tissue.
