STIMULATION OF NUCLEAR POLYPHOSPHOINOSITIDE SYNTHESIS BY GTP-GAMMA-S - A POTENTIAL REGULATORY ROLE FOR NUCLEAR GTP-BINDING PROTEINS

The nonhydrolyzable GTP analogue GTP-gamma-S was capable of stimulatin g in vitro phosphorylation of polyphosphoinositides in isolated nuclei prepared from mouse erythroleukemia cells. On the contrary, GDP-beta- S was ineffective. The stimulation was not detectable when nuclei were prepared from erythroleukemia cells induced to differentiate by expos ure to dimethyl sulfoxide, Both nuclear phosphomonoesterase and phosph olipase C activities were not influenced by GTP-gamma-S. Our results p oint to the likelihood that nuclear phosphoinositide kinases might be regulated by a GTP-binding protein. (C) 1996 Academic Press, Inc.