Inhibition of myosin ATPase activity by human myasthenia gravis antibodies reactive with the acetylcholine receptor.
Antibodies, obtained from myasthenia gravis patients, with reactivity for an immunodominant region of the nicotinic acetylcholine receptor were found to also react with muscle myosin. Since amino acid sequence analyses have previously suggested possible serological relationships between AChR and a head region sequence of myosin heavy chain, cross-reactive antibodies were examined for their ability to interfere with ATPase activities associated with this region of myosin. Results indicated that AChR-specific antibodies purified from MG patient serum by binding to and elution from antigen columns were found to inhibit Ca(2+)-dependent, myosin-associated ATPase activity; interestingly, this inhibition appeared to be relatively selective in that neither K+(EDTA)-dependent nor Mg(2+)-dependent ATPase activities were sensitive to antibody-mediated interference.
Mohan
S
S
Department of Microbiology, University of Texas Health Science Center, San Antonio 78284.
Krolick
K A
KA
D001323:Autoantibodies / Q000276:immunology*; D001666:Binding Sites, Antibody; D002118:Calcium / Q000378:metabolism; D003429:Cross Reactions; D006801:Humans; D009157:Myasthenia Gravis / Q000276:immunology*; D009218:Myosins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000276:immunology* / Q000378:metabolism
D001323:Autoantibodies; D011950:Receptors, Cholinergic; D009218:Myosins; D002118:Calcium