Calmodulin-dependent protein phosphorylation and calcium uptake in rat-liver microsomes.
A 20-kDa protein becomes phosphorylated in a process stimulated by Ca2+ and calmodulin in the light microsomal fraction of rat liver homogenate. The uptake of Ca2+ in light microsomal fraction is also calmodulin-stimulated. The stimulation of Ca2+ transport is associated with the operation of a protein phosphorylation system dependent on Ca2+ and calmodulin. Transport is inhibited by a protein phosphatase which is stimulated by Ca2+ and calmodulin. It is proposed that the phosphorylation of the 20-kDa protein, which is stimulated by Ca2+ and calmodulin, plays a role in the regulation of the microsomal Ca2+, Mg2+-ATPase.
D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000502:physiology*; D004789:Enzyme Activation; D066298:In Vitro Techniques; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010750:Phosphoproteins / Q000096:biosynthesis*; D010766:Phosphorylation; D051381:Rats; D011919:Rats, Inbred Strains
D002147:Calmodulin; D010750:Phosphoproteins; D010749:Phosphoprotein Phosphatases; D002118:Calcium