Table 1.

Main Components of the Mouse Brain Fractions

fraction	main components
H	homogenate containing all cellular components
P1	nuclei, ER, cell-membrane fragments, and blood cells
S1	crude cytosol containing small nuclear fragments, some ER components, small cell-membrane fragments, and most subcellular organelles
P2	nuclei, ER, cell-membrane fragments
S2	crude cytosol containing most subcellular organelles
P3	crude mitochondria plus synaptosomes
S3	cytosolic components including ER
P4	semipurified nonsynaptosomal mitochondria
S4A	buffer-soluble cytosolic biomolecules including proteins
S4B	damaged organelles, myelin, large protein complexes, and associated lipids
S4C	synaptosomes, microsomes, peroxisomes
P5	purified nonsynaptosomal mitochondria
S5	wash of P5
P6	highly purified nonsynaptosomal mitochondria
S6	wash of P6
P7	mitoplasts prepared in the presence of protease inhibitors
S7	wash of P7
P7*	mitochondria treated with digitonin in the presence of protease inhibitors
S7*	wash of P7*