Senior Scientist, Protein Engineering; Phage Display

Janux Therapeutics is seeking a highly skilled Senior Scientist in Protein Engineering to advance our innovative discovery programs. This role requires hands‑on expertise with phage display platforms and antibody discovery and optimization techniques, molecular cloning, library design and construction, DNA sequencing, and cell‑based expression systems. As a key member of our R&D team, reporting to our Director of Research, you will work independently and collaboratively in a fast‑paced biotech environment to deliver high‑quality results under tight timelines.

• Design, construct, and quality‑check phage display libraries used in peptide and antibody‑based screening campaigns targeting diverse antigens.
• Screen synthetic and immune phage libraries for high‑affinity binders.
• Characterize peptide and antibody candidates using biochemical, biophysical, and cell‑based assays (e.g., ELISA, BLI, flow cytometry).
• Develop directed‑evolution libraries and execute screening methods to optimize peptide and antibody formats for improved affinity, stability, and develop ability.
• Collaborate with protein sciences and engineering teams to produce and validate peptide and antibody candidates.
• Analyze sequencing data from phage pools and selected clones to identify lead candidates.
• Maintain accurate and detailed experimental records and present findings in internal meetings.
• Contribute to patent filings, publications, and regulatory documentation as needed.
• Mentor junior scientists and contribute to a culture of scientific excellence and innovation.
• Perform other duties as assigned.

• Ph.D. in Molecular Biology, Biochemistry, Immunology, or related field with 2+ years of relevant industry or postdoctoral experience (or M.S. with 5+ years at Scientist level).
• Hands‑on experience with phage display platforms and antibody selection techniques.
• Strong understanding of antibody structure‑function relationships and engineering strategies.
• Proficiency in molecular cloning, library construction, sequencing, and cell‑based expression systems (bacterial, yeast, mammalian).
• Experience with analytical tools such as ELISA, liquid‑handler automation, plate‑based assays, flow cytometry, and affinity measurements (SPR, BLI).
• Excellent problem‑solving skills and ability to work independently and collaboratively.
• Highly proficient with Excel and molecular biology software (e.g., Geneious).

• Experience with next‑generation sequencing (NGS) analysis of phage libraries.
• Familiarity with other display technologies (e.g., yeast, mammalian, p‑display).
• Knowledge of develop ability profiling (stability, post‑translational modifications, immunogenicity).
• Prior experience in therapeutic antibody development or biologics pipeline.
• Experience with 3D modeling software.

Compensation

Base salary: $144,000 – $153,000 per year, plus stock options, restricted stock units, ESPP, and a target bonus. Comprehensive benefits include medical, dental, vision, supplemental disability insurance, 401(k), life insurance, flexible schedule, vacation, sick time, and relocation assistance.

• 401(k)
• Medical insurance
• Dental insurance
• Vision insurance
• Supplemental disability insurance
• Flexible schedule
• Life insurance
• Flexible vacation
• Sick time
• Incentive stock option plan
• Relocation assistance

• Monday to Friday

• United States (Required)

• On‑site (San Diego, CA)

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.