Separation of two beta gamma subunit complexes of brain GTP-binding proteins composed of distinct gamma subunits.

The gamma subunits of GTP-binding proteins are always associated with beta subunits under physiological conditions, and at least two gamma subunits exist in the brain. We report here that brain beta gamma subunit complexes composed of distinct gamma subunits can be separated by anion exchange chromatography under nondenaturing conditions. One beta gamma complex was composed of a 36-kDa beta subunit and a 6-kDa gamma subunit and the other was composed of 36/35-kDa beta subunits and 4.5-kDa gamma subunit. The 6-kDa gamma subunit was phosphorylated by protein kinase C but the 4.5-kDa gamma subunit was not.