The crystal structure of a self-activating G protein alpha subunit reveals its distinct mechanism of signal initiation.
Sci Signal
; 4(159): ra8, 2011 Feb 08.
Article
em En
| MEDLINE
| ID: mdl-21304159
ABSTRACT
In animals, heterotrimeric guanine nucleotide-binding protein (G protein) signaling is initiated by G protein-coupled receptors (GPCRs), which activate G protein α subunits; however, the plant Arabidopsis thaliana lacks canonical GPCRs, and its G protein α subunit (AtGPA1) is self-activating. To investigate how AtGPA1 becomes activated, we determined its crystal structure. AtGPA1 is structurally similar to animal G protein α 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 α 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.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Transdução de Sinais
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Estrutura Secundária de Proteína
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Proteínas de Arabidopsis
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Subunidades alfa de Proteínas de Ligação ao GTP
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2011
Tipo de documento:
Article