Dr. John Kuriyan, one of the founders of Nurix.
Dr. John Kuriyan, one of the founders of Nurix.

Boston, MA-based Third Rock Ventures and San Francisco, CA-based The Column Group announced yesterday a $21.5M Series B investment round in drug discovery startup Nurix.  The larger investment comes after a 2012 seed round of $6.2M by the same investors.

Nurix is working on novel therapies that target the ubiquitin proteasome system, or UBS, a regulatory pathway that breaks down unwanted proteins in cells.  According to an article in Xconomy yesterday, ubiquitins are like flags that attach themselves to proteins, “marking them for destruction within the proteasome, which are cylindrical chambers that function as disposal and recycling units within the cell.”  (Click here to read the article on Xconomy.com)

The company’s approach is to develop small molecule drugs that can either speed up or slow down protein degradation.  The technique has applications in the fight against numerous diseases, including cancer.

Third Rock Ventures partner Mark Goldsmith, the former CEO and current chairman of Constellation Pharmaceuticals, has been named Nurix’s interim CEO.  Dr. Goldsmith said:

“Our understanding of the fundamental biology of the ubiquitin proteasome system and its role in select cancers and other diseases has grown significantly and continues to expand rapidly….  By combining a high-resolution molecular understanding of the ubiquitin proteasome system with innovative approaches to modulating its components, Nurix is making important progress in unlocking disease targets that have largely eluded drug discovery efforts.”

Nurix was founded by three UBS experts:  John Kuriyan, a professor of molecular and cell biology at UC Berkeley, and an expert in the structural dynamics of ubiquitin ligases, Michael Rape, also a UC Berkeley professor, and expert in the biology of ubiquitin-dependent cell cycle progression and carcinogenesis, and Arthur Weiss, of UC San Francisco, a pioneer in immunology and signal transduction.

The company’s chief scientific officer is Dr. Mark Gallop, founder of XenoPort, Inc., where he and his team discovered Horizant, a treatment for restless leg syndrome.  Also named to the board was Column Group managing partner Dr. David Goeddel.  Dr. Goeddel was the first scientist to be hired by Genentech.

Nurix is headquartered in San Francisco, CA.  Click here to read the official press release.