title: G{alpha}5 subunit-mediated signalling requires a D-motif and the MAPK ERK1 in Dictyostelium.
abstract: The Dictyostelium Galpha5 subunit has been shown to reduce cell viability, inhibit folate chemotaxis and accelerate tip morphogenesis and gene expression during multicellular development. Alteration of the D-motif (mitogen-activated protein kinase docking site) at the amino terminus of the Galpha 5 subunit or the loss of extracellular signal-regulated kinase (ERK)1 diminished the lethality associated with the overexpression or constitutive activation of the Galpha5 subunit. The amino-terminal D-motif of the Galpha5 subunit was also found to be necessary for the reduced cell size, small aggregate formation and precocious developmental gene expression associated with Galpha5 subunit overexpression. This D-motif also contributed to the aggregation delay in cells expressing a constitutively active Galpha5 subunit, but the D-motif was not necessary for the inhibition of folate chemotaxis. These results suggest that the amino-terminal D-motif is required for some but not all phenotypes associated with elevated Galpha5 subunit functions during growth and development and that ERK1 can function in Galpha5 subunit-mediated signal transduction.
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078-3020, USA.
authors.forename: Brent
authors.initials: B
authors.lastname: Raisley
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078-3020, USA.
authors.forename: Hoai-Nghia
authors.initials: HN
authors.lastname: Nguyen
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078-3020, USA.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Hadwiger
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D002633:Chemotaxis; D004023:Dictyostelium / Q000235:genetics / Q000254:growth & development*; D005492:Folic Acid / Q000378:metabolism; D044385:GTP-Binding Protein alpha Subunits / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D044385:GTP-Binding Protein alpha Subunits; C099256:Galpha5 protein, Dictyostelium; D015800:Protozoan Proteins; D005492:Folic Acid; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases