Isolation of selective ³H-chlornaltrexamine-bound complexes, possible opioid receptor components in brains of mice

The nonequilibrium narcotic antagonist, chlornaltrexamine (CNA) was used to bind selectively and covalently pioid specific sites on brain membrane preparations. Selective binding of [³H]CNA occured with a saturation maximum of 185 fmol/mg protein. Bound [³H]CNA was extracted with Triton X-100, dialyzed against Brij 36T, precipitated with trichloroacetic acid and chromatographed on an ultrogel AcA 22 column. The elution profile suggests that this extract contains a minimum of four selective [³H]CNA complexes. At least two of these complexes migrate in a single large peak. Column calibration showed that this peak eluted at 590,000 daltons. One of these specific [³H]CNA complexes elutes at the elution volume of the column and is dialyzable. Finally, putative aggregate of these complexes elutes with the void volume.