Skip to main content
Article thumbnail
Location of Repository

Microinjection of nonmuscle and smooth muscle caldesmon into fibroblasts and muscle cells



Caldesmon is present in a high molecular mass form in smooth muscle and predominantly in a low molecular mass form in nonmuscle cells. Their biochemical properties are very similar. To examine whether these two forms of caldesmon behave differently in cultured cells, we microinjected fluorescently labeled smooth muscle and nonmuscle caldesmons into fibroblasts. Simultaneous injection of both caldesmons into the same cells has revealed that both high and low relative molecular mass caldesmons are quickly (within 10 min) and stably (over 3 d) incorporated into the same structures of microfilaments including stress fibers and membrane ruffles, suggesting that nonmuscle cells do not distinguish nonmuscle caldesmon from smooth muscle caldesmon. The effect of calmodulin on the incorporation of caldesmon has been examined by coinjection of caldesmon with calmodulin. We have found that calmodulin retards the incorporation of caldesmon into stress fibers for a short period (10 min) but not for a longer incubation (30 min). The behavior of caldesmon in developing muscle cells was also examined because we previously observed that caldesmon disappears during myogenesis (Yamashiro, S., R. Ishikawa, and F. Matsumura. 1988. Protoplasma Suppl. 2: 9-21). We have found that, in contrast to its stable incorporation into stress fibers of fibroblasts, caldesmon is unable to be incorporated into thin filament structure (I-band) of differentiated muscle

Topics: Articles
Publisher: The Rockefeller University Press
OAI identifier:
Provided by: PubMed Central
Download PDF:
Sorry, we are unable to provide the full text but you may find it at the following location(s):
  • http://www.pubmedcentral.nih.g... (external link)
  • Suggested articles

    To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.