The GTP-binding proteins, Go and Gi2, of neural cloned cells and their changes during differentiation

The levels of the alpha-subunits of two GTP-binding proteins, Go and Gi2, were determined in neural and nonneural cloned cells by immunoassays. Go alpha was detected in all neural cells and some of nonneural cells, but not in HL-60 leukemic cells and PYS-2 teratocarcinoma-derived cells. The level of Go alpha was highest in the PC12 pheochromocytoma cells. Gi2 alpha was present in all types of cells tested, and its level was highest in the HL-60 cells and relatively high in glioma cells. Treatment of PC12 cells and neuroblastoma x glioma hybrid NG108-15 cells with nerve growth factor and forskolin, respectively, caused the extension of neuronal-like processes and increase in the level of Go alpha by 60-80%, but small changes in the levels of Gi2 alpha.