| Structural highlights
Function
[GPA1_ARATH] Exhibits a fast rate of basal nucleotide exchange. Guanine nucleotide-binding proteins (G proteins) are involved as modulators or transducers in various transmembrane signaling systems. Together with GCR1, may regulate the cell cycle via a signaling cascade that uses phosphatidylinositol-specific phospholipase C (PI-PLC) as an effector and inositol 1,4,5-trisphosphate(IP(3)) as a second messenger. Promotes abscisic acid (ABA) responses in guard cells. But, together with GCR1 and GB1, acts as a negative regulator of ABA during seed germination and early seedling development. Involved in the blue light (BL) signaling. Together with GCR1 and ADT3, required for BL-mediated synthesis of phenylpyruvate and subsequently of phenylalanine (Phe), in etiolated seedlings. Modulates root architecture (e.g. lateral root formation). Negatively regulated by RGS1.[1] [2] [3] [4] [5] [6]
Publication Abstract from PubMed
In animals, heterotrimeric guanine nucleotide-binding protein (G protein) signaling is initiated by G protein-coupled receptors (GPCRs), which activate G protein alpha subunits; however, the plant Arabidopsis thaliana lacks canonical GPCRs, and its G protein alpha subunit (AtGPA1) is self-activating. To investigate how AtGPA1 becomes activated, we determined its crystal structure. AtGPA1 is structurally similar to animal G protein alpha subunits, but our crystallographic and biophysical studies revealed that it had distinct properties. Notably, the helical domain of AtGPA1 displayed pronounced intrinsic disorder and a tendency to disengage from the Ras domain of the protein. Domain substitution experiments showed that the helical domain of AtGPA1 was necessary for self-activation and sufficient to confer self-activation to an animal G protein alpha subunit. These findings reveal the structural basis for a mechanism for G protein activation in Arabidopsis that is distinct from the well-established mechanism found in animals.
The crystal structure of a self-activating G protein {alpha} subunit reveals its distinct mechanism of signal initiation.,Jones JC, Duffy JW, Machius M, Temple BR, Dohlman HG, Jones AM Sci Signal. 2011 Feb 8;4(159):ra8. PMID:21304159[7]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Pandey S, Assmann SM. The Arabidopsis putative G protein-coupled receptor GCR1 interacts with the G protein alpha subunit GPA1 and regulates abscisic acid signaling. Plant Cell. 2004 Jun;16(6):1616-32. Epub 2004 May 21. PMID:15155892 doi:http://dx.doi.org/10.1105/tpc.020321
- ↑ Warpeha KM, Lateef SS, Lapik Y, Anderson M, Lee BS, Kaufman LS. G-protein-coupled receptor 1, G-protein Galpha-subunit 1, and prephenate dehydratase 1 are required for blue light-induced production of phenylalanine in etiolated Arabidopsis. Plant Physiol. 2006 Mar;140(3):844-55. Epub 2006 Jan 13. PMID:16415218 doi:http://dx.doi.org/10.1104/pp.105.071282
- ↑ Pandey S, Chen JG, Jones AM, Assmann SM. G-protein complex mutants are hypersensitive to abscisic acid regulation of germination and postgermination development. Plant Physiol. 2006 May;141(1):243-56. Epub 2006 Mar 31. PMID:16581874 doi:http://dx.doi.org/pp.106.079038
- ↑ Warpeha KM, Upadhyay S, Yeh J, Adamiak J, Hawkins SI, Lapik YR, Anderson MB, Kaufman LS. The GCR1, GPA1, PRN1, NF-Y signal chain mediates both blue light and abscisic acid responses in Arabidopsis. Plant Physiol. 2007 Apr;143(4):1590-600. Epub 2007 Feb 23. PMID:17322342 doi:http://dx.doi.org/10.1104/pp.106.089904
- ↑ Booker KS, Schwarz J, Garrett MB, Jones AM. Glucose attenuation of auxin-mediated bimodality in lateral root formation is partly coupled by the heterotrimeric G protein complex. PLoS One. 2010 Sep 17;5(9). pii: e12833. doi: 10.1371/journal.pone.0012833. PMID:20862254 doi:http://dx.doi.org/10.1371/journal.pone.0012833
- ↑ Jones JC, Duffy JW, Machius M, Temple BR, Dohlman HG, Jones AM. The crystal structure of a self-activating G protein {alpha} subunit reveals its distinct mechanism of signal initiation. Sci Signal. 2011 Feb 8;4(159):ra8. PMID:21304159 doi:10.1126/scisignal.2001446
- ↑ Jones JC, Duffy JW, Machius M, Temple BR, Dohlman HG, Jones AM. The crystal structure of a self-activating G protein {alpha} subunit reveals its distinct mechanism of signal initiation. Sci Signal. 2011 Feb 8;4(159):ra8. PMID:21304159 doi:10.1126/scisignal.2001446
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