FIGURE 1.

Assessment of mitochondrial purity. A, electron photomicrograph of a mitochondrial pellet reveals a sample rich in mitochondria and lacking other recognizable intracellular organelles. Scale bar = 500 nm. B, Western blot revealing both NR1 and NR2a labeling in cytosolic (C) and mitochondrial (M) samples. There was no labeling of the cytoplasmic marker β-actin, the endosomal marker LAMP1, or the endoplasmic reticulum marker calnexin (Cal) in the cytochrome oxidase IV (COX IV)-labeled mitochondrial fraction. C, there was considerably more NR2a labeling in the synaptic membrane fraction (S) compared with the mitochondrial fraction. The marker for plasma membrane (ATPase) was virtually absent in the mitochondrial fraction, and the marker for synaptic vesicles (Syn) was only minimally present.