Abstract
The delivery of Met-tRNAi to the 40S ribosomal subunit is thought to occur by way of a ternary complex (TC) comprising eIF2, GTP and Met-tRNAi. We have generated from purified human proteins a stable multifactor complex (MFC) comprising eIF1, eIF2, eIF3 and eIF5, similar to the MFC reported in yeast and plants. A human MFC free of the ribosome also is detected in HeLa cells and rabbit reticulocytes, indicating that it exists in vivo. In vitro, the MFC-GTP binds Met-tRNAi and delivers the tRNA to the ribosome at the same rate as the TC. However, MFC-GDP shows a greatly reduced affinity to Met-tRNAi compared to that for eIF2-GDP, suggesting that MFC components may play a role in the release of eIF2-GDP from the ribosome following AUG recognition. Since an MFC-Met-tRNAi complex is detected in cell lysates, it may be responsible for Met-tRNAi-40S ribosome binding in vivo, possibly together with the TC. However, the MFC protein components also bind individually to 40S ribosomes, creating the possibility that Met-tRNAi might bind directly to such 40S-factor complexes. Thus, three distinct pathways for Met-tRNAi delivery to the 40S ribosomal subunit are identified, but which one predominates in vivo remains to be elucidated.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 905-913 |
| Number of pages | 9 |
| Journal | Nucleic Acids Research |
| Volume | 40 |
| Issue number | 2 |
| DOIs | |
| State | Published - Jan 2012 |
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Cite this
The human translation initiation multi-factor complex promotes methionyl-tRNA i binding to the 40S ribosomal subunit. / Sokabe, Masaaki; Fraser, Christopher S.; Hershey, John W B.
In: Nucleic Acids Research, Vol. 40, No. 2, 01.2012, p. 905-913.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The human translation initiation multi-factor complex promotes methionyl-tRNA i binding to the 40S ribosomal subunit
AU - Sokabe, Masaaki
AU - Fraser, Christopher S.
AU - Hershey, John W B
PY - 2012/1
Y1 - 2012/1
N2 - The delivery of Met-tRNAi to the 40S ribosomal subunit is thought to occur by way of a ternary complex (TC) comprising eIF2, GTP and Met-tRNAi. We have generated from purified human proteins a stable multifactor complex (MFC) comprising eIF1, eIF2, eIF3 and eIF5, similar to the MFC reported in yeast and plants. A human MFC free of the ribosome also is detected in HeLa cells and rabbit reticulocytes, indicating that it exists in vivo. In vitro, the MFC-GTP binds Met-tRNAi and delivers the tRNA to the ribosome at the same rate as the TC. However, MFC-GDP shows a greatly reduced affinity to Met-tRNAi compared to that for eIF2-GDP, suggesting that MFC components may play a role in the release of eIF2-GDP from the ribosome following AUG recognition. Since an MFC-Met-tRNAi complex is detected in cell lysates, it may be responsible for Met-tRNAi-40S ribosome binding in vivo, possibly together with the TC. However, the MFC protein components also bind individually to 40S ribosomes, creating the possibility that Met-tRNAi might bind directly to such 40S-factor complexes. Thus, three distinct pathways for Met-tRNAi delivery to the 40S ribosomal subunit are identified, but which one predominates in vivo remains to be elucidated.
AB - The delivery of Met-tRNAi to the 40S ribosomal subunit is thought to occur by way of a ternary complex (TC) comprising eIF2, GTP and Met-tRNAi. We have generated from purified human proteins a stable multifactor complex (MFC) comprising eIF1, eIF2, eIF3 and eIF5, similar to the MFC reported in yeast and plants. A human MFC free of the ribosome also is detected in HeLa cells and rabbit reticulocytes, indicating that it exists in vivo. In vitro, the MFC-GTP binds Met-tRNAi and delivers the tRNA to the ribosome at the same rate as the TC. However, MFC-GDP shows a greatly reduced affinity to Met-tRNAi compared to that for eIF2-GDP, suggesting that MFC components may play a role in the release of eIF2-GDP from the ribosome following AUG recognition. Since an MFC-Met-tRNAi complex is detected in cell lysates, it may be responsible for Met-tRNAi-40S ribosome binding in vivo, possibly together with the TC. However, the MFC protein components also bind individually to 40S ribosomes, creating the possibility that Met-tRNAi might bind directly to such 40S-factor complexes. Thus, three distinct pathways for Met-tRNAi delivery to the 40S ribosomal subunit are identified, but which one predominates in vivo remains to be elucidated.
UR - http://www.scopus.com/inward/record.url?scp=84855867417&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84855867417&partnerID=8YFLogxK
U2 - 10.1093/nar/gkr772
DO - 10.1093/nar/gkr772
M3 - Article
C2 - 21940399
AN - SCOPUS:84855867417
VL - 40
SP - 905
EP - 913
JO - Nucleic Acids Research
JF - Nucleic Acids Research
SN - 0305-1048
IS - 2
ER -