Role of secondary phosphoinositide messengers in storage of Ca2+ ions in retinal rod microsomes

The influence of guanosine-5'-triphosphate and secondary messengers forming in rod outer segment membranes during light-stimulated hydrolysis of phosphoinositides on the ATP-dependent Ca(2+)-uptake in microsomes of the retinal rod inner segment was studied. The water-soluble cytoplasmic components of the retinal rod outer segment were shown to be capable of stimulating the Ca(2+)-pump of endoplasmic reticulum after light illumination. This process is likely to proceed with the participation of 1,2-diacylglycerol localized in microsome membrane.