Molecular chaperoning function of Ric-8 is to fold nascent heterotrimeric G protein α subunits.
Proc Natl Acad Sci U S A
; 110(10): 3794-9, 2013 Mar 05.
Article
em En
| MEDLINE
| ID: mdl-23431197
We have shown that resistance to inhibitors of cholinesterase 8 (Ric-8) proteins regulate an early step of heterotrimeric G protein α (Gα) subunit biosynthesis. Here, mammalian and plant cell-free translation systems were used to study Ric-8A action during Gα subunit translation and protein folding. Gα translation rates and overall produced protein amounts were equivalent in mock and Ric-8A-immunodepleted rabbit reticulocyte lysate (RRL). GDP-AlF4(-)-bound Gαi, Gαq, Gα13, and Gαs produced in mock-depleted RRL had characteristic resistance to limited trypsinolysis, showing that these G proteins were folded properly. Gαi, Gαq, and Gα13, but not Gαs produced from Ric-8A-depleted RRL were not protected from trypsinization and therefore not folded correctly. Addition of recombinant Ric-8A to the Ric-8A-depleted RRL enhanced GDP-AlF4(-)-bound Gα subunit trypsin protection. Dramatic results were obtained in wheat germ extract (WGE) that has no endogenous Ric-8 component. WGE-translated Gαq was gel filtered and found to be an aggregate. Ric-8A supplementation of WGE allowed production of Gαq that gel filtered as a â¼100 kDa Ric-8A:Gαq heterodimer. Addition of GTPγS to Ric-8A-supplemented WGE Gαq translation resulted in dissociation of the Ric-8A:Gαq heterodimer and production of functional Gαq-GTPγS monomer. Excess Gßγ supplementation of WGE did not support functional Gαq production. The molecular chaperoning function of Ric-8 is to participate in the folding of nascent G protein α subunits.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Chaperonas Moleculares
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Fatores de Troca do Nucleotídeo Guanina
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Subunidades alfa de Proteínas de Ligação ao GTP
Limite:
Animals
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Humans
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
Estados Unidos