Worm Breeder's Gazette 3(2): 25

These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.

Myosins Exist as Homodimers of Heavy Chains: Demonstration with Specific Antibody Purified by Nematode Mutant Mysosin Affinity Chmtghpy

F. Schachat, R.L. Garcea, H.F. Epstein

The body-walls of Caenorhabditis two 
different myosin heavy chains that associate to form at least two 
species of myosin.  In order to better define the distribution of 
these heavy chains in myosin molecules, we have characterized the 
myosin of C.  elegans by immunochemical methods.  Specific, 
precipitating anti-myosin antibody has been prepared in rabbits using 
highly purified nematode myosin as the immunogen.  The difference in 
reactivity of the anti-myosin antibody with wild-type myosin 
containing both kinds of heavy chains (designated unc-54 and non-unc-
54 heavy chains on the basis of genetic specification) and myosin from 
the mutant E190 that lacks unc-54 heavy chain indicates that there are 
antigenic differences between myosin molecules containing unc-54 heavy 
chains and myosin molecules containing only non-unc-54 myosin heavy 
chains.  Antibody specific for the unc-54 myosin determinants has been 
prepared by the immunoadsorption of anti-myosin antibody with E190 
myosin.  This specific antiunc-54 myosin antibody precipitates myosin 
that contains only unc-54 heavy chains.  At the limits of resolution 
of our immunoprecipitation techniques, no heterodimeric myosin 
molecules that contain both unc-54 and non-unc-54 heavy chains can be 
detected.  Therefore, the body-wall myosins of C.  elegans exist only 
as homodimers of either class of heavy chain.
This specific anti-unc-54 myosin antibody promises to be a valuable 
tool in understanding the role of two myosins in body-wall muscle and 
in molecular characterizations of mutant myosins in C.  elegans.  We 
report here the use of this antibody to detect antigenic differences 
between unc-54 myosin from the wild-type and the muscle mutant E675.  
In conjunction with the original anti-myosin antibody, other studies 
show that both unc-54 and non-unc-54 myosins exist within the same 
body-wall muscle cells (See Mackenzie, Schachat and Epstein) and that 
both myosins are coordinately synthesized during muscle development in 
C.  elegans (See Garcea, Schachat and Epstein).