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Principal Scientist / Sr. Scientist, Protein Engineering

As member of the Research group, the Scientist will help execute and manage the production of recombinant proteins to support the discovery and advancement of Janux molecules. The successful candidate will be knowledgeable and experienced in the processes of mammalian cell transfection, stable pool isolation and expansion, as well as protein purification and quality controls. The ideal Scientist will lead the upstream cell culture and downstream protein purification research efforts. Part of this role includes the direct guidance and support of other team members in the execution of the protein production process at Janux.


  • Ph.D. in Cell and Molecular Biology, Biotechnology, Bioengineering or a related discipline + 5 year of postdoctoral / industry experience OR an M.S. + 10 years of industry experience in protein production groups.
  • Experience with molecular biology methods for mammalian cell culture
  • Experience using multiple transfection methods and selection markers for recombinant protein expression in CHO and HEK293 cells.
  • Ability to isolate and expand stable pools from transient transfections.
  • Hands-on experience in mammalian cell culture methods and aseptic techniques
  • Working knowledge and experience with downstream protein purification is required
  • Hands-on experience with research scale purification using AKTA FPLC systems, affinity chromatography, and additional polishing steps
  • Knowledge around additional bioanalytical methods for protein quality control
  • Experience working with CROs to outsource some protein production if necessary is a plus
  • Strong analytical skills and ability to work in a highly collaborative environment
  • Excellent written and oral communication skills.


  • Leads and executes hands-on transfection of mammalian cells and cell culture in support of recombinant protein production at the research scale
  • Leads and executes protein purification efforts using standard chromatography methods and techniques on AKTA FPLC systems
  • Maintenance and organization of plasmid and protein electronic databases, including electronic protein reports and batch records is required.
  • Isolation of stable pools from transient transfections is also required from time to time
  • Tracks and communicates the protein production, purification, and QC timing on a daily basis to senior manager in order to efficiently support priority projects and timelines.
  • Maintains detailed records of all experiments performed. Writes SOPs and technical documents to support research efforts as necessary.
  • Responsible for operation and preventive maintenance of key laboratory equipment within the protein production group.
  • Effectively analyzes, organizes and communicates experimental results to colleagues and senior leadership.
  • Trains and mentors junior members of the team and collaborates across functional areas.


In addition to a competitive compensation package with stock options, Janux also offers a comprehensive benefits package for our employees and their families, which includes medical, dental, vision, and supplemental disability insurance.

Job Type: Full-time


  • 401K
  • Medical insurance
  • Dental insurance
  • Vision insurance
  • Supplemental disability insurance plans
  • Flexible schedule
  • Life insurance
  • Flexible vacation
  • Sick time
  • Incentive stock option plan
  • Schedule:
  • Monday to Friday

Work authorization:

  • United States (Required)

Additional Compensation:

  • Annual targeted bonus %

Work Location:

  • On site required – La Jolla / Torrey Pines
  • Working remotely not available

Company’s website:

  • www.januxrx.com

COVID-19 Vaccination required

Janux requires all new hires to be fully vaccinated for COVID-19 prior to the first date of employment.  As required by applicable law, Janux will consider requests for Reasonable Accommodations.


Janux Therapeutics, Inc. is an equal opportunity employer that is committed to providing a work environment free of harassment and discrimination based upon a protected category, as well as an environment free from retaliation for protected activity.