Regulation and function of Gα protein subunits in Dictyostelium

Kumagai, Akiko; Pupillo, M.; Gundersen, Robert E.; Miake-Lye, Richard C.; Devreotes, Peter N.; Firtel, Richard A.

doi:10.1016/0092-8674(89)90964-1

Cited by 270 publications

(275 citation statements)

References 38 publications

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“…In mammals, it is not certain which of the ␤␥-complexes is key, whereas in D. discoideum, there is a single ␤-subunit. Genetic evidence shows that ␣2 and ␤ are essential for many responses to chemoattractants; it is expected that the G␥ is also essential (Kumagai et al, 1989;Wu et al, 1995). However, the anticipated G␥ has not been identified in spite of considerable effort by degenerate PCR analysis and database searching.…”

Section: Introductionmentioning

confidence: 99%

“…Evidence suggests that it is the ␤␥-complexes, released by receptor-catalyzed exchange of GTP for GDP on ␣-subunits, which directly regulate effectors (Wu et al, 1995;Neptune et al, 1997;. The specific G-proteins involved in chemotaxis consist of ␣ i in mammals and ␣2 or ␣4 in D. discoideum (Kumagai et al, 1989;Hadwiger et al, 1994). In mammals, it is not certain which of the ␤␥-complexes is key, whereas in D. discoideum, there is a single ␤-subunit.…”

Section: Introductionmentioning

confidence: 99%

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Gγ inDictyostelium: Its Role in Localization of Gβγ to the Membrane Is Required for Chemotaxis in Shallow Gradients

Zhang

Lan

Devreotes

2001

MBoC

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Monitoring Editor: Joan S. Brugge 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 G␣-subunits, a single G␤-subunit, but no G␥-subunits. We report here the purification, cDNA isolation, and functional analysis of a G␥-subunit. Like G␤, the G␥ appears to be unique and hybridization studies show that G␥ and G␤ are expressed in parallel during development. Species-wide sequence comparisons of G␥-subunits and ␥-like domains of RGS proteins reveal short stretches of highly conserved residues as well as the common CXXL motif at the COOHterminal of G␥s that target G␤␥s to plasma membrane. Overexpression of a CSVL-deleted G␥ (G␥⌬) in wild-type cells shifts G␤␥ to the cytosol and selectively impairs certain G-proteinmediated 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 G␤␥ is required for sensing shallow gradients, but is not essential for responses to increments in extracellular stimuli.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Gγ inDictyostelium: Its Role in Localization of Gβγ to the Membrane Is Required for Chemotaxis in Shallow Gradients

Zhang

Lan

Devreotes

2001

MBoC

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“…Such analyses have allowed the evaluation and placement of potential effectors in the activation pathway of ACA. Although ACA can not be activated by cAMP in cells lacking either Gα2 or Gβ, gα2-nulls are fully responsive to GTPγS, whereas gβ-nulls are insensitive (Kumagai et al, 1991;Wu et al, 1995). Data suggest that while ACA activation requires CAR1/G protein signaling, this appears to be mediated via Gβγ, and not by Gα2.…”

Section: The Adenylyl Cyclases (Acs)mentioning

confidence: 93%

“…Gβ is absolutely essential for cAMP signaling, aggregation, and development. Gα2 is the principal Gα protein that interacts with CAR1 during aggregation, and among the cell lines deleted for a single Gα, only gα2-nulls are developmentally blocked (Kumagai et al, 1989;Kumagai et al, 1991). The primary, but not sole, function of Gα2 may be to ensure βγsignal transduction, rather than to directly activate a downstream effector in its GTP-bound state (Pupillo et al, 1992).…”

Section: G Proteins Camp Affinity and Adaptationmentioning

confidence: 99%

“…Direct activation of G proteins with GTPγS also induces their uncoupling from CAR1 and the loss of high affinity cAMP binding. By these criteria there are relatively few high affinity sites in gα2-nulls (Kumagai et al, 1991), but they can be partially restored by overexpression of another CAR1-binding Gα protein, Gα9 (Brzostowski et al, 2004).…”

Section: G Proteins Camp Affinity and Adaptationmentioning

confidence: 99%

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Oscillatory signaling and network responses during the development of Dictyostelium discoideum

McMains

Liao

Kimmel

2008

Ageing Research Reviews

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Periodic biological variations reflect interactions among molecules and cells, or even organisms. The Dictyostelium cAMP oscillatory circuit is a highly robust example. cAMP oscillations in Dictyostelium arise intracellularly by a complex interplay of activating and inhibiting pathways, are transmitted extracellularly, and synchronize an entire local population. Once established, cAMP signal-relay persists stably for hours. On a two-dimensional surface, >100,000 cells may form a single coordinated territory. In suspension culture, >10 10 cells can oscillate in harmony. This review focuses on molecular mechanisms that cyclically activate and attenuate signal propagation and on chemotactic responses to oscillatory wave progression.

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Phosphorylation of the G protein α-subunit, Gα2, ofDictyostelium discoideum requires a functional and activated Gα2

Gundersen

1997

J. Cell. Biochem.

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The G alpha 2-subunit of Dictyostelium discoideum is essential to the initial stage of the cell's developmental life cycle. In response to the extracellular chemoattractant, cAMP, G alpha 2 is activated and transiently phosphorylated on serine-113 [Chen et al. (1994): J Biol Chem 269:20925-20930]. The role of G alpha 2 phosphorylation remains elusive; cells expressing the S113A, nonphosphorylated mutation of G alpha 2 appear to proceed through the developmental phase normally. To gain insight into the function of G alpha 2 phosphorylation, the conditions for G alpha 2 phosphorylation were examined using a variety of alpha-subunit point mutations and chimeras. Mutations that block the G protein activation cycle prior to or at the hydrolysis of GTP (G alpha 2-S45A, G alpha 2-G207A, and G alpha 2-Q208L) preclude G alpha 2 phosphorylation in vivo. Phosphorylation of the G alpha 2-Q208L mutation does however occur in an in vitro phosphorylation assay. It appears that G alpha 2 phosphorylation, shown previously in vivo to require the cAMP receptor, also requires signaling through the G2 pathway. Results from the in vitro assay suggest that the substrate for phosphorylation is the alpha-subunit monomer.

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Regulation and function of Gα protein subunits in Dictyostelium

Cited by 270 publications

References 38 publications

Gγ inDictyostelium: Its Role in Localization of Gβγ to the Membrane Is Required for Chemotaxis in Shallow Gradients

Gγ inDictyostelium: Its Role in Localization of Gβγ to the Membrane Is Required for Chemotaxis in Shallow Gradients

Oscillatory signaling and network responses during the development of Dictyostelium discoideum

Phosphorylation of the G protein α-subunit, Gα2, ofDictyostelium discoideum requires a functional and activated Gα2

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