We identify a novel myosin-binding protein, designated 53K, which appears to mediate the low ionic strength solubility of myosin in extracts of unfertilized sea urchin eggs. The protein possesses a subunit molecular mass on SDS-PAGE of 53 kD, an S value of 7, may be organized into disulfide-linked oligomers, and is associated with myosin in egg extracts. Both myosin and 53K co-precipitate from extract upon the addition of nucleoside triphosphates and co-sediment with an S value of 24 by sedimentation velocity centrifugation. Myosin in extracts not associated with 53K has an S value of 10. Further, myosin can be immunoprecipitated from extract with antibody to 53K and the 53K in extracts binds to a myosin affinity column. When extract is depleted of 53K, a majority of the myosin precipitates out of extract in a nucleotide-independent manner. Whereas purified myosin precipitates in the absence of nucleotide when recombined with dialysis buffer or myosin-depleted extract, reconstituting 53K and myosin before addition to buffer or myosin-depleted extract partially restores the low ionic strength solubility demonstrated by myosin in fresh egg extracts. The 53-kD protein may represent a new class of authentic myosin-binding proteins that may regulate the supramolecular organization of myosin in nonmuscle cells.
Article| August 01 1987
Low ionic strength solubility of myosin in sea urchin egg extracts is mediated by a myosin-binding protein.
D R Burgess
Online ISSN: 1540-8140
Print ISSN: 0021-9525
J Cell Biol (1987) 105 (2): 927–936.
R Yabkowitz, D R Burgess; Low ionic strength solubility of myosin in sea urchin egg extracts is mediated by a myosin-binding protein.. J Cell Biol 1 August 1987; 105 (2): 927–936. doi: https://doi.org/10.1083/jcb.105.2.927
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