PT  - JOURNAL ARTICLE
AU  - ANDREW P. SMITH
AU  - HORACE H. LOH
TI  - Multiple Molecular Forms of Stereospecific Opiate Binding
DP  - 1979 Nov 01
TA  - Molecular Pharmacology
PG  - 757--766
VI  - 16
IP  - 3
4099  - http://molpharm.aspetjournals.org/content/16/3/757.short
4100  - http://molpharm.aspetjournals.org/content/16/3/757.full
SO  - Mol Pharmacol1979 Nov 01; 16
AB  - When brain membranes were incubated in vitro with 3H-enkephalinamide, then extracted with the non-ionic detergent Brij 36-T, up to 75% of the levorphanol-displaceable radioactivity was released in a bound form. Analysis of the binding material by gel filtration revealed a broad peak of 100,000-500,000 molecular weight, and several other species of less than 20,000 molecular weight. Iso-electric focusing resolved the binding components into two major peaks of pI’s about 8.4 and 3.2, and several minor species in the pI range 8.3-6.5; both high and low molecular weight material appeared to be present in the two major pI peaks. All of the stereospecific binding components identified by iso-electric focusing appeared to behave similarly with respect to several competing unlabeled drugs, and to Na+ ion. Comparable heterogeneity was observed in material stereospecifically binding 3H-βH-endorphin, 3H-etorphine, and 3H-naloxone, and incubation of Brij-extracted 3H-βH-endorphin-binding membranes with 10 mM dimethyl suberimidate covalently labeled a broad range of species of 2-200 x 103 molecular weight. These results demonstrate that many distinct brain membrane components can bind opiates stereospecifically in vitro; these components may include lipids as well as proteins. ACKNOWLEDGMENT We thank Drs. Richard Houghten and C. H. Li for the gift of tritiated βH-endorphin.