Conclusions and Future Perspectives

We have summarized those bioenergetical processes which we applied to GPCR signalling, and presented a new model for transmembrane signal transduction mediated via (ligand-induced) GPCR and G protein activation. The classical model for G protein activation is based on an exchange mechanism followed by GTP hydrolysis. Our new model is based on GTP synthesis from GDP and Pi, also followed by GTP hydrolysis. Because of amplification levels (1) (synthesis) and (3) (exchange) depicted in Figure 7.1, both the classical and our new model will give rise to similar nucleotide exchange patterns.