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The association of initiation factor (eIF)4F with poly(A)-binding protein is enhanced in serum-stimulated Xenopus kidney cells

journal contribution
posted on 2023-06-08, 07:14 authored by Christopher S Fraser, Virginia M Pain, Simon Morley
Serum stimulation of cultured Xenopus kidney cells results in enhanced phosphorylation of the translational initiation factor (eIF) 4E and promotes a 2.8-fold increase in the binding of the adapter protein eIF4G to eIF4E, to form the functional initiation factor complex eIF4F. Here we demonstrate the serum-stimulated co-isolation of the poly(A)-binding protein (PABP) with the eIF4F complex. This apparent interaction of PABP with eIF4F suggests that a mechanism shown to be important in the control of translation in the yeast Saccharomyces cerevisiae also operates in vertebrate cells. We also present evidence that the signaling pathways modulating eIF4E phosphorylation and function in Xenopus kidney cells differ from those in several mammalian cell types studied previously. Experiments with the immunosuppressant rapamycin suggest that the mTOR signaling pathway is involved in serum-promoted eIF4E phosphorylation and association with eIF4G. Moreover, we could find little evidence for regulation of eIF4E function via interaction with the specific binding proteins 4E-BP1 or 4E-BP2 in these cells. Although rapamycin abrogated serum-enhanced rates of protein synthesis and the interaction of eIF4G with eIF4E, it did not prevent the increase in association of eIF4G with PABP. This suggests that serum stimulates the interaction between eIF4G and PABP by a distinct mechanism that is independent of both the mTOR pathway and the enhanced association of eIF4G with eIF4E

History

Publication status

  • Published

Journal

Journal of Biological Chemistry

ISSN

00219258

Publisher

Journal of Biological Chemistry

Issue

1

Volume

274

Page range

196-204

ISBN

0021-9258

Department affiliated with

  • Biochemistry Publications

Full text available

  • No

Peer reviewed?

  • Yes

Legacy Posted Date

2012-02-06

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