Intermolecular versus intramolecular interactions of Dictyostelium myosin: possible regulation by heavy chain phosphorylation.

C. Pasternak*, P. F. Flicker, S. Ravid, J. A. Spudich

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

75 Scopus citations

Abstract

Dictyostelium myosin has been examined under conditions that reveal intramolecular and intermolecular interactions that may be important in the process of assembly and its regulation. Rotary shadowed myosin molecules exhibit primarily two configurations under these conditions: straight parallel dimers and folded monomers. All of the monomers bend in a specific region of the 1860-A-long tail that is 1200 A from the head-tail junction. Molecules in parallel dimers are staggered by 140 A, which is a periodicity in the packing of myosin molecules originally observed in native thick filaments of muscle. The most common region for interaction in the dimers is a segment of the tail about 200-A-long, extending from 900 to 1100 A from the head-tail junction. Parallel dimers form tetramers by way of antiparallel interactions in their tail regions with overlaps in multiples of 140 A. The folded configuration of the myosin molecules is promoted by phosphorylation of the heavy chain by Dictyostelium myosin heavy chain kinase. It appears that the bent monomers are excluded from filaments formed upon addition of salt while the dimeric molecules assemble. These results may provide the structural basis for primary steps in myosin filament assembly and its regulation by heavy chain phosphorylation.

Original languageAmerican English
Pages (from-to)203-210
Number of pages8
JournalJournal of Cell Biology
Volume109
Issue number1
DOIs
StatePublished - Jul 1989
Externally publishedYes

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