TY - JOUR
T1 - eIF4G is required for the pioneer round of translation in mammalian cells
AU - Lejeune, Fabrice
AU - Ranganathan, Aparna C.
AU - Maquat, Lynne E.
N1 - Funding Information:
We thank M. Coldwell, L. McKendrick and S. Morley for pmyc-eIF4GI (1–1600) and derivatives, pBS-His-CBP80, anti-eIF4G and anti-PAPB; N. Sonenberg for anti-eIF4GII, pCMV-HA-eIF4GII and pcDNA3-HA-eIF4AIII; P. Mitchell and D. Tollervey for anti-Rrp4; K. Borden for the GST-eIF4E expression vector; J. Lewis for pRSET-CBP20; H. Baumann and B. Held for anti-MUP; T. Ohlmann for HIV-1 and HIV-2 protease expression vectors and R. Lloyd for the polio 2A protease expression vector. We are grateful to R. Lloyd, T. Ohlmann and S. Cusack for helpful conversations, Y.K. Kim for comments on the manuscript, and M. Kmieciak for help generating figures. This work was supported by US National Institutes of Health grants to L.E.M.
PY - 2004/10
Y1 - 2004/10
N2 - Nonsense-mediated mRNA decay (NMD) in mammalian cells targets cap-binding protein 80 (CBPBO)-bound mRNA during or after a pioneer round of translation. It is unknown whether eukaryotic translation initiation factor 4G (eIF4G) functions in the pioneer round. We show that baculovirus-produced CBP80 and CBP20 independently interact with eIF4GI. The interactions between eIF4G and the heterodimer CBP80/20 suggest that eIF4G has a function in the pioneer initiation complex rather than merely a presence during remodeling to the steady-state complex. First, NMD is inhibited upon eIF4G cleavage by HIV-2 or poliovirus 2A pro tease. Second, eIF4GI coimmunopurifies with pre-mRNA, indicating that it associates with transcripts before the pioneer round. Third, eIF4G immunopurifies with Upf NMD factors and eIF4AIII, which are constituents of the pioneer translation initiation complex. We propose a model in which eIF4G serves to connect CBP80/20 with other initiation factors during the pioneer round of translation.
AB - Nonsense-mediated mRNA decay (NMD) in mammalian cells targets cap-binding protein 80 (CBPBO)-bound mRNA during or after a pioneer round of translation. It is unknown whether eukaryotic translation initiation factor 4G (eIF4G) functions in the pioneer round. We show that baculovirus-produced CBP80 and CBP20 independently interact with eIF4GI. The interactions between eIF4G and the heterodimer CBP80/20 suggest that eIF4G has a function in the pioneer initiation complex rather than merely a presence during remodeling to the steady-state complex. First, NMD is inhibited upon eIF4G cleavage by HIV-2 or poliovirus 2A pro tease. Second, eIF4GI coimmunopurifies with pre-mRNA, indicating that it associates with transcripts before the pioneer round. Third, eIF4G immunopurifies with Upf NMD factors and eIF4AIII, which are constituents of the pioneer translation initiation complex. We propose a model in which eIF4G serves to connect CBP80/20 with other initiation factors during the pioneer round of translation.
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U2 - 10.1038/nsmb824
DO - 10.1038/nsmb824
M3 - Article
C2 - 15361857
AN - SCOPUS:4744347153
VL - 11
SP - 992
EP - 1000
JO - Nature Structural Biology
JF - Nature Structural Biology
SN - 1545-9993
IS - 10
ER -