the results obtained in these experiments suggest that at least four kinds of calcium exist in bound from in the cell , i. e. , ( 1 ) loosely and ( 2 ) tightly bound calcium on the external surface of the cell membrane , ( 3 ) calcium localized in the internal surface of the cell membrane and ( 4 ) calcium stored in the intracellular store site , such as the sarcoplasmic reticulum .
C0007634
cell
C0036226
sarcoplasmic reticulum