G proteins, short for guanine nucleotide-binding proteins, are a family of proteins involved in second messenger cascades. G proteins are so called because they function as "molecular switches". They alternate from 'inactive' guanosine diphosphate (GDP) to 'active' guanosine triphosphate (GTP), which is a binding state, and which proceeds to regulate downstream cell processes. Source: [[wikipedia:G_protein|Wikipedia]] This pathway was inferred from Homo sapiens pathway [http://www.wikipathways.org/index.php?title=Pathway:WP35&amp;amp;oldid=20751 WP35(r20751)] with a 94% conversion rate. a71 d70 G protein mediated signaling pathway PW:0000125 Pathway Ontology 12040175 PubMed G protein pathways. Science 2002 Neves SR Ram PT Iyengar R 3103658 PubMed G proteins: a family of signal transducers. Annu Rev Cell Biol 1986 Stryer L Bourne HR