Western blotting of brain homogenates. Lanes: 1, human RBC ghosts; 2, human platelets; 3–8, brain homogenates, separated into 30,000 × g pellet (P) and supernatant (S) fractions: 3, +/+ P; 4, +/+ S; 5, +/− P; 6, +/− S; 7, −/− P; 8, −/− S. β-1 is not detected in −/− samples, but α and γ are detected in all samples.