2xtz

Crystal structure of the G alpha protein AtGPA1 from Arabidopsis thaliana

spinqualitylabelsall models 2xtz, resolution 2.34Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2xtz is a 3 chain structure with sequence from Arabidopsis thaliana. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.34Å Ligands: CL, CSS, GSP, MG, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT 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. 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 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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