HETEROGENEITY OF 3 ELECTROPHORETICALLY DISTINCT-GO ALPHA-SUBUNITS IN MAMMALIAN BRAIN

So far three splice variants of the alpha(o)-gene coding for two alpha(o) proteins have been identified by molecular cloning, and the corresponding proteins purified. In the present study subtype-specific peptide antibodies revealed the existence of an electrophoretically distinct third form of alpha(o) in mammalian brain membranes which migrates more slowly on SDS-PAGE and shows a more acidic pI value than the other alpha(o)-subunits. Each of the three alpha(o)-subunits is detected as two isoforms when enriched from brain membranes. Rodent alpha(o)-subunits differ from non-rodent species in their electrophoretic mobilities. The results suggest that (i) there may exist a novel alpha(o)-subunit which reacts with an alpha(o)-subunit-specific antibody, (ii) each alpha(o)-subunit may exist in more than one co- or posttranslationally modified isoform in brain membranes, and (iii) differences between alpha(o)-subunits from different species exist which are detectable by gel electrophoretic methods.