Preliminary investigation of sequence-independent DNA binding proteins in rat skeletal muscle sarcoplasmic reticulum and their function

To observe the binding of plasmid DNA to cion-nuclear DNA binding proteins in sarcoplasmic reticulum (SR) and the effects of this binding on SR functi on, sarcoplasmic reticulum proteins in rat skeletal muscle were isolated by differential centrifuge and sucrose density-gradient centrifuge. The resul ts showed that there are two sequence-independent DNA binding proteins in S R proteins, the molecular weights of which are 83 and 58 ku, respectively. Ca2+ uptake and release of SR were remarkably promoted by the binding of pl asmid DNA to DNA binding proteins in SR, the mechanism is probably through increasing of Ca2+-ATPase activity in SR and changing of character of Ca2release channel ryanodine receptors induced by the binding. These results s uggest that there exist DNA binding proteins in SR and its binding to DNA m ay affect Ca2+ transport of SR.