Fig. 3.
Differential centrifugation of cortical membrane fractions reveals dopamine receptor distribution across distinct cellular subdomains. Fractions are designated as: S, synaptosomal fraction (12,500g pellet); P, plasma membrane fraction (23,000g pellet); μ, microsomal membrane fraction (100,000g sediment); R, ribosomal fraction (300,000g sediment); and Cy, cytoplasmic fraction (300,000g supernatant). A, D1 receptors are restricted to Dr membranes of various buoyancies throughout the cell. B, D5 receptors are visualized primarily in the 300,000g cytoplasmic fraction. C, D2 receptors are observed in every fraction examined, with varying percentages in the Ds versus Dr fractions. Blots were reprobed for PSD-95 and calnexin to validate the efficiency of fractionation.