Site-specific inhibition of myosin-mediated motility in vitro by monoclonal antibodies

Paula F. Flicker, Gary Peltz, Michael P. Sheetz, Peter Parham, James A. Spudich

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


Monoclonal antibodies directed against seven different sites on Dictyostelium myosin (Peltz, G., J. A. Spudich, and P. Parham, 1985, J. Cell Biol., 100: 1016-1023) were tested for their ability to inhibit movement of myosin in vitro, using the Nitella-based myosinmediated bead movement assay (Sheetz, M. P., R. Chasan, and J. A. Spudich, 1984, J. Cell Biol., 99: 1867-1871). To complement this functional assay, we located the binding sites of these antibodies by electron microscopy, using the rotary shadowing technique. One antibody bound to the 18,000-dalton light chain and inhibited movement completely. All of the remaining antibodies bound to various positions along the rod portion of the myosin molecule, which is ≈1,800 A long. Antibodies that bound to the rod about 470, 680, and 1400 A from the head-tail junction did not alter myosin movement. One antibody appeared to bind very close to the head-tail junction and to inhibit movement 50%. Surprisingly, three antibodies that bound about 1,200 A from the head-tail junction inhibited movement completely. This inhibition did not depend on using intact IgG, since Fab’ fragments had the same effect.

Original languageEnglish (US)
Pages (from-to)1024-1030
Number of pages7
JournalJournal of Cell Biology
Issue number4
StatePublished - Apr 1 1985
Externally publishedYes

ASJC Scopus subject areas

  • Cell Biology


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