The role of myosin phosphorylation in histamine secretion from rat basophil leukemic (RBL) cells has been investigated. In unstimulated cells histamine secretion was about 1% of the total cell content and the stoichiometry of myosin phosphorylation was 1 mol phosphate/mol heavy chain and 0.4 mol phosphate/mol light chain. In the case of the myosin light chains, all of the phosphate was confined to a single site known to be phosphorylated by myosin light chain kinase. Upon stimulation for 10 min with DNP-BSA, the amount of histamine secretion from the cells reached 40-50% of the total content and the stoichiometry of phosphorylation was 1.78 mol phosphate/mol heavy chain and 0.84 mol phosphate/mol light chains. In this case, two distinct populations of light chains were detected: monophosphorylated and diphosphorylated, each of which contained a mixture of sites phosphorylated by myosin light chain kinase and protein kinase C. We are currently investigating the effect of specific inhibitors/activators of these two kinases in order to establish the specific role of myosin phosphorylation in histamine secretion from these cells.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Intramural Research (Z01)
Project #
1Z01HL004209-04
Application #
3899243
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
4
Fiscal Year
1989
Total Cost
Indirect Cost
Name
U.S. National Heart Lung and Blood Inst
Department
Type
DUNS #
City
State
Country
United States
Zip Code