A Series of Molecular Signals That Proceeds with an Activated Receptor Promoting the Exchange of GDP For GTP On the Alpha Subunit of an Associated Heterotrimeric G Protein Complex. the GTP Bound Activated Alpha G Protein Then Dissociates From the Beta and Gamma Subunits to Further Transmit the Signal Within the Cell. the Pathway Begins with Receptor Ligand Interaction or For Basal Gpcr Signaling the Pathway Begins with the Receptor Activating Its G Protein in the Absence of an Agonist and Ends with Regulation of a Downstream Cellular Process E.g. Transcription. the Pathway Can Start From the Plasma Membrane Golgi or Nuclear Membrane (pmid:24568158 and Pmid:16902576).
Combining with an Extracellular Signal and Transmitting the Signal Across the Membrane by Activating an Associated G Protein; Promotes the Exchange of GDP For GTP On the Alpha Subunit of a Heterotrimeric G Protein Complex.