The G protein α subunit (GPα1) is associated with the ER and the plasma membrane in meristematic cells of <i>Arabidopsis</i> and cauliflower

Weiss, Catherine; White, Elyssa; Huang, Hai; Mā, Hong

doi:10.1016/s0014-5793(97)00378-5

Cited by 45 publications

(37 citation statements)

References 33 publications

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“…Cell fractionation and immunofluorescence studies demonstrate that GP␣1 localizes to the ER and plasma membrane in meristematic cells of Arabidopsis and cauliflower (Weiss et al, 1997). In tobacco embryos a similar distribution is observed (Kaydamov et al, 2000).…”

Section: Introductionmentioning

confidence: 84%

Plant G protein heterotrimers require dual lipidation motifs of Gα and Gγ and do not dissociate upon activation

Adjobo‐Hermans

Goedhart

Gadella

2006

Journal of Cell Science

111

117

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In plants one bona fide Gα subunit has been identified, as well as a single Gβ and two Gγ subunits. To study the roles of lipidation motifs in the regulation of subcellular location and heterotrimer formation in living plant cells, GFP-tagged versions of the Arabidopsis thaliana heterotrimeric G protein subunits were constructed. Mutational analysis showed that the Arabidopsis Gα subunit, GPα1, contains two lipidation motifs that were essential for plasma membrane localization. The Arabidopsis Gβ subunit, AGβ1, and the Gγ subunit, AGG1, were dependent upon each other for tethering to the plasma membrane. The second Gγ subunit, AGG2, did not require AGβ1 for localization to the plasma membrane. Like AGG1, AGG2 contains two putative lipidation motifs, both of which were necessary for membrane localization. Interaction between the subunits was studied using fluorescence resonance energy transfer (FRET) imaging by means of fluorescence lifetime imaging microscopy (FLIM). The results suggest that AGβ1 and AGG1 or AGβ1 and AGG2 can form heterodimers independent of lipidation. In addition, FLIM-FRET revealed the existence of GPα1-AGβ1-AGG1 heterotrimers at the plasma membrane. Importantly, rendering GPα1 constitutively active did not cause a FRET decrease in the heterotrimer, suggesting no dissociation upon GPα1 activation.

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Section: Introductionmentioning

confidence: 84%

Plant G protein heterotrimers require dual lipidation motifs of Gα and Gγ and do not dissociate upon activation

Adjobo‐Hermans

Goedhart

Gadella

2006

Journal of Cell Science

111

117

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“…The inset illustrates the Dex-inducible expression of GPA1 as described in "Materials and Methods." Upper, Immunoblot probed with antiserum directed against recombinant GPA1 (Weiss et al, 1997); lower, nonspecific band recognized by the anti-GPA serum. Samples were either treated (ϩ) or not (Ϫ) with Dex.…”

Section: Gpa1 Seedlings Have Altered Brassinolide and Sugar Sensitivimentioning

confidence: 99%

“…GPA1 over expressing (H2 line) and control (containing empty vector) Arabidopsis seedlings were grown on onehalf-strength Murashige and Skoog plates (plus or minus 1.0 m Dex) at 23°C under continuous light for 8 d. Membrane proteins (20 g) were extracted from the whole seedlings and subjected to immunoblot analysis with a polyclonal antiserum against recombinant GPA1 (Weiss et al, 1997). The blots were visualized using the SuperSignal West Pico chemiluminescent substrate (Pierce Chemical, Rockford, IL).…”

Section: Aba Analysismentioning

confidence: 99%

Role of a Heterotrimeric G Protein in Regulation of Arabidopsis Seed Germination

et al. 2002

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Seed germination is regulated by many signals. We investigated the possible involvement of a heterotrimeric G protein complex in this signal regulation. Seeds that carry a protein null mutation in the gene encoding the alpha subunit of the G protein in Arabidopsis (GPA1) are 100-fold less responsive to gibberellic acid (GA), have increased sensitivity to high levels of Glc, and have a near-wild-type germination response to abscisic acid and ethylene, indicating that GPA1 does not directly couple these signals in germination control. Seeds ectopically expressing GPA1 are at least a million-fold more responsive to GA, yet still require GA for germination. We conclude that the GPA1 indirectly operates on the GA pathway to control germination by potentiation. We propose that this potentiation is directly mediated by brassinosteroids (BR) because the BR response and synthesis mutants, bri1-5 and det2-1, respectively, share the same GA sensitivity as gpa1 seeds. Furthermore, gpa1 seeds are completely insensitive to brassinolide rescue of germination when the level of GA in seeds is reduced. A lack of BR responsiveness is also apparent in gpa1 roots and hypocotyls suggesting that BR signal transduction is likely coupled by a heterotrimeric G protein at various points in plant development.Seeds integrate many intrinsic signals to control germination (Koornneef et al., 2002). For example, since the original observation by Chrispeels and Varner (1966), it has been repeatedly shown that GA induces germination and that abscisic acid (ABA) antagonizes the GA effect (Koornneef and Van der Veen, 1980;Karssen et al., 1989; Gilroy and Jones, 1994;Ritchie and Gilroy, 1998;Lovegrove and Hooley, 2000). Seed germination of GA synthesis mutants can be rescued by the application of GA and ABA synthesis and insensitive mutants lack the ABA inhibition of GA-induced germination as well as being viviparous (Koornneef et al., 1982(Koornneef et al., , 1984 Finkelstein and Somerville, 1990;Koornneef and Karssen, 1994;Leon-Kloosterziel et al., 1996). Brassinosteroid (BR) probably acts downstream of GA because BR is able to rescue germination of GA-deficient (Steber and McCourt, 2001) and GA response (Steber et al., 1998) mutant seeds. These authors argue that the BR input is likely to reside upstream of ABA's attenuating effect on GA-induced germination because BR synthesis and response mutants have slightly altered ABA sensitivity.The inhibitory effect of high concentrations of sugars on germination may occur via ABA. The evidence supporting this comes from measurements of ABA in Glc-treated seedlings (Arenas-Huertero et al., 2000) and from the observation that ABA synthesis and response mutants are insensitive to Glc (Laby et al., 2000;Rook et al., 2001). Ethylene controls the Glc inhibition of germination (Zhou et al., 1998). Evidence supporting this includes the observations that high concentrations of ethylene antagonize the Glc repression of germination (Ghassemian et al., 2000), the ctr1 (constitutive ethylene response mutant; Gibs...

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“…In Arabidopsis meristematic cells, GPA1 is present in the endoplasmic reticulum (ER), Golgi and plasma membranes, but not in nuclei or chloroplasts (Weiss et al 1997). Similarly, Ga and Gb were localized to the plasma membrane and ER in embryo and endosperm tissue of Nicotiana plumbaginifolia (Kaydamov et al 2000).…”

Section: Introductionmentioning

confidence: 99%

Expression analysis and subcellular localization of the Arabidopsis thaliana G-protein β-subunit AGB1

Anderson

Botella

2007

Plant Cell Rep

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Heterotrimeric GTP-binding proteins (G-proteins), consisting of Ga, Gb, and Gc subunits, function as molecular switches in many eukaryotic signal transduction pathways. In contrast to many eukaryotes, plants contain very few G-protein subunit isoforms that mediate a diverse array of signalling functions. We investigated the contribution of cell type-specific expression and subcellular localization to this multifunctional signalling capacity for the Arabidopsis thaliana Gb subunit, AGB1. Analysis of AGB1 promoter::b-glucuronidase (GUS) fusions in germinating seeds, seedlings, and flowering plants revealed that AGB1 is widely expressed throughout development in a complex manner. As well as demonstrating similarities to existing Arabidopsis G-protein subunit expression data, several features of the AGB1 expression pattern align closely with known or proposed G-protein functions. A C-terminal AGB1-green fluorescent protein (GFP) fusion was localized at the plasma membrane and in the nucleus of leaf epidermal cells, trichomes and root cells, supporting previous evidence that plant G-protein functionality relies on subcellular compartmentalization.

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The G protein α subunit (GPα1) is associated with the ER and the plasma membrane in meristematic cells of Arabidopsis and cauliflower

Cited by 45 publications

References 33 publications

Plant G protein heterotrimers require dual lipidation motifs of Gα and Gγ and do not dissociate upon activation

Plant G protein heterotrimers require dual lipidation motifs of Gα and Gγ and do not dissociate upon activation

Role of a Heterotrimeric G Protein in Regulation of Arabidopsis Seed Germination

Expression analysis and subcellular localization of the Arabidopsis thaliana G-protein β-subunit AGB1

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