G protein signaling components in filamentous fungal genomes

Abstract

In fungi, heterotrimeric G proteins regulate a number of critical developmental processes including growth, mating and pathogenesis. Signals may originate from extracellular ligands or from internal sources. These signals are conveyed from G protein coupled receptors (GPCRs) or nonreceptor guanine nucleotide exchange factors (GEFs) to a heterotrimeric G protein composed of α, β and γ subunits. GPCRs and nonreceptor GEFs activate the Gα subunit, causing the disassociation of the heterotrimer. Both the Gα and Gβγ heterodimer are free to act upon downstream effectors. Two prominent output pathways are the cyclic adenosine monophosphate (cAMP) and mitogen-activated protein kinase (MAPK) pathways. Changes in growth, mating and pathogenesis can be initiated through G protein signals and executed downstream by these or as yet uncharacterized signaling pathways.