Comparative Characteristics of Sarcoplasmic Reticulum Preparations from Skeletal Muscles of the Ground Squirrel Spermophilus undulatus, Rats and Rabbit

摘要

At a comparison of sarcoplasmic reticulum (SR) preparations from skeletal muscles of the ground squirrels Spermophilus undulatus rats, and rabbites is established that on a protein yield and on a phospholipid/protein ratio these preparations practically do not differ. At the same time the specific activity of Ca-ATPase, the main protein component of SR membranes, is approsimately twice lower in SR preparations of the ground squirrel skeletal muscles than in SR preparations of rats and rabbits. The significant differences in protein composition of the preparations are detected: ground squirrel SR differs by unusually high content of 205 kDa protein and a number of SR low molecular weight protein components, and the SR preparations of rabbits are characterized by the high content of Ca-binding proteins calsequestrin and sarcalumenin. With the use of anionic carbocyanine dye Stains-All is established that all preparations contain only three proteins which are stained by this dye in dark blue colour: calsequestrin, sarcalumenin, and histidine-rich Ca-binding protein. Electrophoretic mobility of calsequestrin is identical in all preparations, whereas sarcalumenin and histidine-rich Ca-binding protein are presented, probably, by different isoforms: their molecular masses are equal 130, 145 and 160 and 165, 155 and 170 kDa, respectively, in SR preparations of ground squirrels, rats and rabbits. The analysis of fluorescence parameters of fluorescent probes 8-anilino-1-naphtalene sulphonic acid and pyrene bound to SR membranes has shown that the properties of lipid bilayer of SR membranes of the preparations considerably differ. It is suggested that the differences in protein composition and/or structural state of ground squirrel SR membrane lipid bilayer can be the reason of low Ca-ATPase activity in these preparations.