the results of an electron microscopic histochemical investigation performed in the current study indicate that in heart cells creatine phosphokinase is localized : ( 1 ) inside mitochondria mainly on the cristae membranes , ( 2 ) on the membrane of the sarcoplasmic reticulum , ( 3 ) on myofibrils ( and in cytoplasm ) , ( 4 ) on the plasma membrane of the cells , ( 5 ) on the membrane of the cell nuclei .
C0010834
cytoplasm
C0007603
plasma membrane