TY - JOUR
T1 - Gγ in Dictyostelium
T2 - Its role in localization of Gβγ to the membrane is required for chemotaxis in shallow gradients
AU - Zhang, N.
AU - Long, Y.
AU - Devreotes, P. N.
PY - 2001
Y1 - 2001
N2 - G-protein-mediated signal transduction pathways play an essential role in the developmental program of the simple eukaryotic organism Dictyostelium discoideum. Database searches have yielded 11 Gα-subunits, a single Gβ-subunit, but no Gγ-subunits. We report here the purification, cDNA isolation, and functional analysis of a Gγ-subunit. Like Gβ, the Gγ appears to be unique and hybridization studies show that Gγ and Gβ are expressed in parallel during development. Species-wide sequence comparisons of Gγ-subunits and γ-like domains of RGS proteins reveal short stretches of highly conserved residues as well as the common CXXL motif at the COOH-terminal of Gγs that target Gβγs to plasma membrane. Overexpression of a CSVL-deleted Gγ (Gγδ) in wild-type cells shifts Gβγ to the cytosol and selectively impairs certain G-protein-mediated signal transduction pathways. These cells are able to respond to increments in the stimulus, but are unable to sense chemoattractant gradients. They neither move directionally nor recruit PH-domains to their leading edge. Thus, a full complement of membrane-tethered Gβγ is required for sensing shallow gradients, but is not essential for responses to increments in extracellular stimuli.
AB - G-protein-mediated signal transduction pathways play an essential role in the developmental program of the simple eukaryotic organism Dictyostelium discoideum. Database searches have yielded 11 Gα-subunits, a single Gβ-subunit, but no Gγ-subunits. We report here the purification, cDNA isolation, and functional analysis of a Gγ-subunit. Like Gβ, the Gγ appears to be unique and hybridization studies show that Gγ and Gβ are expressed in parallel during development. Species-wide sequence comparisons of Gγ-subunits and γ-like domains of RGS proteins reveal short stretches of highly conserved residues as well as the common CXXL motif at the COOH-terminal of Gγs that target Gβγs to plasma membrane. Overexpression of a CSVL-deleted Gγ (Gγδ) in wild-type cells shifts Gβγ to the cytosol and selectively impairs certain G-protein-mediated signal transduction pathways. These cells are able to respond to increments in the stimulus, but are unable to sense chemoattractant gradients. They neither move directionally nor recruit PH-domains to their leading edge. Thus, a full complement of membrane-tethered Gβγ is required for sensing shallow gradients, but is not essential for responses to increments in extracellular stimuli.
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U2 - 10.1091/mbc.12.10.3204
DO - 10.1091/mbc.12.10.3204
M3 - Article
C2 - 11598203
AN - SCOPUS:0034746777
SN - 1059-1524
VL - 12
SP - 3204
EP - 3213
JO - Molecular biology of the cell
JF - Molecular biology of the cell
IS - 10
ER -