Acanthamoeba myosin I heavy chain kinase is activated by phosphatidylserine-enhanced phosphorylation.
Year: 1990
Type: article
Abstract: The actin-activated Mg2(+)-ATPase activities of myosins I from Acanthamoeba castellanii are fully expressed only when a single amino acid on their heavy chain is phosphorylated by myosin I heavy chain kinase. Here we show that kinase isolated by a procedure designed to minimize its phosphorylation during purification can incorporate up to 7.5 mol of phosphate/mol of enzyme when incubated with ATP, possibly by autophosphorylation. The rate of phosphorylation is enhanced about 20-fold by phosphatidylserine but is unaffected by calcium ions. Phosphorylation increases the rate at which the kinase phosphorylates the regulatory site of myosin I by about 50-fold. These results suggest that (auto?)phosphorylation may regulate the activity of myosin I heavy chain kinase in vivo. The stimulation of kinase phosphorylation by phosphatidylserine (other phospholipids have not yet been tested) is of particular interest because myosin I has been shown to be tightly associated with membranes, especially the plasma membrane.
Source: Journal of Biological Chemistry
Authors: H Brzeska, T J Lynch, E D Korn
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W1485407235