Heterotrimeric G-protein beta-subunit is localized in the plasma membrane and nuclei of tobacco leaves

Heterotrimeric G-proteins are involved in a variety of cellular responses, but relatively little is known about their function and biochemistry in pla nts. Antibodies raised against the tobacco heterotrimeric G-protein beta-su bunit (G beta) were used to analyse its distribution in tobacco leaves. In young tissue the protein level was relatively high, while it declined subst antially during later stages of leaf development. Cell fractionation reveal ed that G beta is tightly associated with plasma membrane, but can also be detected in purified nuclei.