Regulation of phospholipase A(2) activity in cockroach (Periplaneta americana) fat body by hypertrehalosemic hormone: evidence for the participation of protein kinase C.
Phospholipase A(2) (PLA(2)) associated with the membrane fraction of trophocytes from Periplaneta americana fat body increases by as much as 100% when the cells are incubated with hypertrehalosemic hormone (HTH-II). Activation with HTH-II is approximately halved by inclusion of the PKC inhibitor sphingosine in the incubation medium. Because activation of PLA(2) by HTH-II is blocked by the GDP analogue GDP-beta-S, and the unactivated enzyme is activated by the GTP analogue GTP-gamma-S it is likely that a G protein is involved in activation of the enzyme. Activation of PLA(2) was also achieved by treating the trophocytes with the synthetic diacylglycerol 1-oleoyl-2-acetylglycerol in the presence of thapsigargin. This supports the view that protein kinase C is also involved in the activation process.
Sun
D
D
Department of Zoology, The University of Western Ontario, N6A 5B7, London, ON, Canada
Steele
J E.
JE