LOCALIZATION OF VARIOUS FORMS OF THE GAMMA-SUBUNIT OF G-PROTEIN IN NEURAL AND NONNEURAL TISSUES

For a study of the localization of various forms of the gamma subunit of G proteins, antibodies were raised in rabbits against peptides that corresponded to partial amino acid sequences of bovine gamma(2), gamm a(3), gamma(5) and gamma(7). Affinity-purified antibodies against gamm a(2), gamma(3) and gamma(5) reacted specifically with gamma(2), gamma( 3), and gamma(5), respectively, but the antibody against gamma(7) reac ted with gamma(2), gamma(3), and a novel gamma subunit, designated gam ma(s1), as well as with gamma(7). Because these antibodies reacted wit h the respective forms of the gamma subunit from rat brain, we investi gated the localization of gamma subunits in the rat. gamma(2) and gamm a(3) were abundant in all regions in the brain, whereas the concentrat ion of gamma(5) and gamma(7) was relatively low with the single except ion being a high concentration of gamma(7) in the striatum. The concen tration of gamma(2) was consistently high during ontogenic development in the rat brain, whereas gamma(3) appeared about a week after birth and their concentrations then increased until a month after birth. In tissues other than the brain, gamma(3) was observed only in the pituit ary gland, whereas gamma(2), gamma(5), and gamma(7) were found in a va riety of tissues. In addition, most tissues contained relatively high concentrations of some other gamma subunit, which was detected with an antibody against a gamma(7)-derived peptide and appeared to be gamma( s1). Among cloned cells tested, gamma(3) was detected only in PC12 phe ochromocytoma cells. Taken together, the results indicated that gamma( 3) was expressed specifically in neuronal cells, and gamma(s1) was the major gamma subunit in most nonneural cells. gamma(2), gamma(5), and gamma(7) were distributed in a variety of tissues, but gamma(2) was do minant in the brain.