FIGURE 3.

p250, p160, and Mα monomers have distinct Stokes radii that are minimally altered by solubilization in detergents with different micelle sizes. MNT-1 cells were lysed using n-octylglucoside (A–C), dodecyl-β-d-maltoside (D–F), or Triton X-100 (G–I), and the detergent extracts were fractionated by size exclusion chromatography in the corresponding detergent. A, D, and G, eluted fractions were analyzed by SDS-PAGE under non-reducing (NR) conditions and immunoblotted using the HMB45 antibody. Shown are regions of the immunoblots corresponding to p250, p160, Mα+Mβ′, and Mα as indicated to the left. Fraction numbers are indicated above each lane, and the migration of α₂-macroglobulin is indicated with an arrow. Note that immunoblot contrast was optimally adjusted for each individual species in each experiment. B, E, and H, HMB45 immunoreactivity was quantified to determine the elution volume of p250, p160, Mα+Mβ′, and Mα. The lowest value quantified for each species was set to 0% and the highest value was set to 100%. C, F, and I, the Stokes radius of each species was then calculated by comparing the peak elution fraction of that species with those of globular protein standards in three independent experiments. Circles, values calculated from each experiment; open circles, values calculated from the experiments shown in A, D, and G; horizontal lines, mean value; error bars, S.D. Mean ± S.D. are also shown in Table 1.