The yeast hsp70 homologue Ssa is required for translation and interacts with Sis1 and Pab1 on translating ribosomes.
J Biol Chem
; 276(17): 14426-33, 2001 Apr 27.
Article
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| MEDLINE
| ID: mdl-11279042
The 70-kDa heat shock proteins are molecular chaperones that participate in a variety of cellular functions. This chaperone function is stimulated by interaction with hsp40 proteins. The Saccharomyces cerevisiae gene encoding the essential hsp40 homologue, SIS1, appears to function in translation initiation. Mutations in ribosomal protein L39 (rpl39) complement loss-of-function mutations in SIS1 as well as PAB1 (poly(A)-binding protein), suggesting a functional interaction between these proteins. However, while a direct interaction between Sis1 and Pab1 is not detectable, both of these proteins physically interact with the essential Ssa (and not Ssb) family of hsp70 proteins. This interaction is mediated by the variable C-terminal domain of Ssa. Subcellular fractionations demonstrate that the binding of Ssa to ribosomes is dependent upon its C terminus and that its interaction with Sis1 and Pab1 occurs preferentially on translating ribosomes. Consistent with a function in translation, depletion of Ssa protein produces a general translational defect that appears similar to loss of Sis1 and Pab1 function. This translational effect of Ssa appears mediated, at least in part, by its affect on the interaction of Pab1 with the translation initiation factor, eIF4G, which is dramatically reduced in the absence of functional Ssa protein.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Ribosomas
/
Biosíntesis de Proteínas
/
Proteínas de Unión al ARN
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Proteínas HSP70 de Choque Térmico
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Proteínas de Saccharomyces cerevisiae
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Proteínas de Choque Térmico
Idioma:
En
Revista:
J Biol Chem
Año:
2001
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos