Related Experiment Video
Updated: Mar 6, 2026

Protein-protein Interactions Visualized by Bimolecular Fluorescence Complementation in Tobacco Protoplasts and Leaves
Published on: March 9, 2014
Guanosine triphosphate-binding proteins on the plasmalemma of spinach leaf cells
Pierre Crespi1, Pierre-François Perroud1, Hubert Greppin1
1Laboratoire de Biochimie et Physiologie Végétales, Université de Genève, Place de l'Université 3, CH-1211, Genève 4, Switzerland.
Abstract:
The molecular mechanism of light perception through phytochrome is not well understood. This red-light photosensor has been implicated in various physiological processes, including the photoinduction of flowering. A few recent studies have shown that phytochrome initiates signal transduction chains via guanosine triphosphate (GTP)-binding proteins (G-proteins). We show here by different approaches that G-proteins exist in spinach (Spinacia oleracea L. cv. Nobel). Binding of GTP on the plasmalemma has been partially characterized and its possible regulation by red light examined by in-vitro assays. These experiments indicate a clear regulation of GTP binding by red light and also by Mastoparan. At least three G-proteins or protein subunits were found to be associated with the plasmalemma of leaf cells. The use of an antibody raised against an animal Gβ subunit confirmed the presence of heterotrimeric G-proteins. Separation of a crude membrane extract by free-flow electrophoresis also showed that some G-proteins could exist on the tonoplast.
Related Concept Videos
GTPases and their Regulation
Large G-proteins,...
Protein Transport to the Inner Chloroplast Membrane
Protein Transport to the Outer Chloroplast Membrane
Two models describe the mechanism of precursor recognition and entry across the outer membrane through the TOC complex. Model 1 suggests the newly synthesized precursor binds to the TOC receptor 159 and forms a complex.
Protein Transport to the Stroma
Protein complexes called the translocon of the outer chloroplast membrane or TOC complex, and the translocon of the inner chloroplast membrane or TIC complex mediate the...
Coat Assembly and GTPases
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Cell Signaling in Plants

