Hiroki Nojima
First author of the 2003 Kobe study showing that raptor grabs mTOR's targets through a short TOS motif, the docking step that lets mTORC1 reach its substrates
Biosignal Research Center, Kobe University, Kazuyoshi Yonezawa group (at the time of the study, 2003)
An enzyme like mTOR has to find the right proteins to act on. In 2002 two groups discovered raptor, a partner protein that sits next to mTOR in the complex now called mTORC1, the growth-control complex. One of those groups was Kazuyoshi Yonezawa's team at Kobe University. Hiroki Nojima was first author of their 2003 follow-up in the Journal of Biological Chemistry (NOJ2003).
The study showed that raptor binds two of mTOR's best-known targets, p70 S6 kinase and 4E-BP1, both of which control how fast cells make proteins. Raptor holds them through a short stretch of five amino acids called the TOS motif (TOR signalling motif). When the motif was changed, raptor could no longer bind and mTOR could no longer act on the target. This made raptor the part of mTORC1 that presents substrates to the kinase, a model that has held up in later structural work. The experiments were done in cultured cells and with purified proteins.
PubMed lists Nojima at the Biosignal Research Center of Kobe University. No other paper could be tied to this person with confidence, so later career steps are not known.
Milestones in the Atlas
A selection, not a full bibliography: only papers that meet the Atlas inclusion criteria.
| Year | Evidence | Study |
|---|---|---|
| 2003 | M | The mammalian target of rapamycin (mTOR) partner, raptor, binds the mTOR substrates p70 S6 kinase and 4E-BP1 through their TOR signaling (TOS) motif NOJ2003 First author: showed that raptor binds S6 kinase and 4E-BP1 through their TOS motifs, which lets mTORC1 present these substrates to the kinase. |
Co-authors in the Atlas 6
People with a profile here who share at least one study with Hiroki Nojima.
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- Chiharu Tokunaga Member of Kazuyoshi Yonezawa's Kobe team that co-discovered raptor, and first author of a 2004 review on how mTOR combines amino acid and energy signals
- Joseph Avruch Showed in 1998 that amino acids, not only insulin, are needed for mTOR to activate S6K1 and 4E-BP1. His Massachusetts General Hospital group, with Kazuyoshi Yonezawa's lab in Kobe, then co-discovered raptor in 2002 and found that Rheb binds mTOR directly
- Kazuyoshi Yonezawa Led the Kobe University group that co-discovered raptor in 2002, in parallel with the Sabatini lab. His team then showed that raptor binds mTOR's substrates through their TOS motif and that PRAS40 is itself an mTORC1 substrate
- Kenta Hara Showed in 1998 that amino acids are needed for mTOR to activate S6K1 and 4E-BP1, and as first author co-discovered raptor in 2002
- Noriko Oshiro-Rapley In one of several 2007 studies, identified PRAS40 as a raptor-bound mTORC1 substrate that gates access to mTORC1's other substrates
- Sujuti Hidayat Member of Kazuyoshi Yonezawa's Kobe team that co-discovered raptor and worked out how mTOR senses amino acids, and first author of a study showing that a leucine derivative can block amino acid-mTOR signalling
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