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The C terminus of initiation factor 4E-binding protein 1 contains multiple regulatory features that influence its function and phosphorylation

The C terminus of initiation factor 4E-binding protein 1 contains multiple regulatory features that influence its function and phosphorylation
The C terminus of initiation factor 4E-binding protein 1 contains multiple regulatory features that influence its function and phosphorylation
Eukaryotic initiation factor 4E (eIF4E) binds the mRNA cap structure and forms eIF4F complexes that recruit 40S subunits to the mRNA. Formation of eIF4F is blocked by eIF4E-binding proteins such as 4E-BP1, which interacts with eIF4E via a motif in the center of its 118-residue sequence. 4E-BP1 plays key roles in cell proliferation, growth, and survival. Binding of 4E-BP1 to eIF4E is regulated by hierarchical multisite phosphorylation. Here we demonstrate that three different features in the C terminus of 4E-BP1 play distinct roles in regulating its phosphorylation and function. Firstly, we identify a new phosphorylation site in its C terminus (S101). A serine or glutamate at this position is required for efficient phosphorylation at Ser65. A second C-terminal site, S112, directly affects binding of 4E-BP1 to eIF4E without influencing phosphorylation of other sites. Thirdly, a conserved C-terminal motif influences phosphorylation of multiple residues, including rapamycin-insensitive sites. These relatively long-range effects are surprising given the reportedly unstructured nature of 4E-BP1 and may imply that phosphorylation of 4E-BP1 and/or binding to eIF4E induces a more-ordered structure. 4E-BP2 and -3 lack phosphorylatable residues corresponding to both S101 and S112. However, in 4E-BP3, replacement of the alanine at the position corresponding to S112 by serine or glutamate did not confer the ability to be released from eIF4E in response to insulin.
0270-7306
1546-1557
Wang, Xuemin
530099a8-90dc-47de-8315-9c2f6f11a569
Li, Wei
ab5e097b-b347-4edf-95dd-2b245edf0f81
Parra, Josep-Lluis
2de70b9d-ef74-4aa8-a475-ce12fddf3939
Beugnet, Anne
78e2ba75-1730-4a12-bfdd-9e13903d19e2
Proud, Christopher G.
59dabfc8-4b44-4be8-a17f-578a58550cb3
Wang, Xuemin
530099a8-90dc-47de-8315-9c2f6f11a569
Li, Wei
ab5e097b-b347-4edf-95dd-2b245edf0f81
Parra, Josep-Lluis
2de70b9d-ef74-4aa8-a475-ce12fddf3939
Beugnet, Anne
78e2ba75-1730-4a12-bfdd-9e13903d19e2
Proud, Christopher G.
59dabfc8-4b44-4be8-a17f-578a58550cb3

Wang, Xuemin, Li, Wei, Parra, Josep-Lluis, Beugnet, Anne and Proud, Christopher G. (2003) The C terminus of initiation factor 4E-binding protein 1 contains multiple regulatory features that influence its function and phosphorylation. Molecular and Cellular Biology, 23 (5), 1546-1557. (doi:10.1128/MCB.23.5.1546-1557.2003).

Record type: Article

Abstract

Eukaryotic initiation factor 4E (eIF4E) binds the mRNA cap structure and forms eIF4F complexes that recruit 40S subunits to the mRNA. Formation of eIF4F is blocked by eIF4E-binding proteins such as 4E-BP1, which interacts with eIF4E via a motif in the center of its 118-residue sequence. 4E-BP1 plays key roles in cell proliferation, growth, and survival. Binding of 4E-BP1 to eIF4E is regulated by hierarchical multisite phosphorylation. Here we demonstrate that three different features in the C terminus of 4E-BP1 play distinct roles in regulating its phosphorylation and function. Firstly, we identify a new phosphorylation site in its C terminus (S101). A serine or glutamate at this position is required for efficient phosphorylation at Ser65. A second C-terminal site, S112, directly affects binding of 4E-BP1 to eIF4E without influencing phosphorylation of other sites. Thirdly, a conserved C-terminal motif influences phosphorylation of multiple residues, including rapamycin-insensitive sites. These relatively long-range effects are surprising given the reportedly unstructured nature of 4E-BP1 and may imply that phosphorylation of 4E-BP1 and/or binding to eIF4E induces a more-ordered structure. 4E-BP2 and -3 lack phosphorylatable residues corresponding to both S101 and S112. However, in 4E-BP3, replacement of the alanine at the position corresponding to S112 by serine or glutamate did not confer the ability to be released from eIF4E in response to insulin.

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Published date: March 2003

Identifiers

Local EPrints ID: 56211
URI: http://eprints.soton.ac.uk/id/eprint/56211
ISSN: 0270-7306
PURE UUID: 80607159-1bdc-408d-ae42-e45c3755cde1

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Date deposited: 07 Aug 2008
Last modified: 15 Mar 2024 11:00

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Contributors

Author: Xuemin Wang
Author: Wei Li
Author: Josep-Lluis Parra
Author: Anne Beugnet
Author: Christopher G. Proud

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