Sr. Associate Scientist; I​/II), Protein Production

Mosaic Biosciences is a biotherapeutics drug discovery company that partners with biopharmaceutical companies to discover novel protein and antibody therapeutics. Our experienced and dedicated research teams collaborate with our partners to design, manage, and execute research programs to rapidly advance clinical candidates, starting at any point from early discovery into preclinical development.

Mosaic is seeking a full-time Sr. Associate Scientist I or Sr. Associate Scientist II to join our Protein Production team in our Boulder, Colorado laboratory. The successful candidate will play a key role in executing and optimizing protein expression and purification workflows while collaborating within a cross‑functional scientific team.

This position requires strong hands‑on laboratory expertise, the ability to troubleshoot experimental challenges independently, and a commitment to delivering high‑quality data in support of client discovery programs.

• Execute and optimize protocols for recombinant protein expression in mammalian, bacterial and/or insect systems.
• Perform protein purification using multi‑step chromatography strategies (e.g., IMAC, SEC, IEX, HIC) and automated chromatography systems (e.g., AKTA PURE).
• Troubleshoot protein expression, purification, and stability challenges using sound scientific reasoning.
• Analyze experimental results and propose adjustments to protocols to improve yield, purity, and reproducibility.
• Ensure experimental work aligns with project scope, quality standards, and milestone timelines.
• Collaborate with cross‑functional teams to support protein supply for discovery and characterization programs.
• Identify potential technical risks and communicate challenges or delays that may impact project timelines.
• Maintain accurate and detailed laboratory documentation for all experimental activities.
• Contribute to laboratory organization, equipment maintenance, and continuous improvement of team workflows.

• Hands‑on experience with recombinant protein expression and purification
  .
• Ability to independently execute experiments, analyze results, and troubleshoot technical challenges.
• Strong organizational skills, attention to detail, and ability to manage multiple priorities.
• Effective written and verbal communication skills and ability to collaborate within scientific teams.
• Aseptic technique / mammalian cell culture experience strongly preferred.
• Experience with automated protein purification systems (e.g., AKTA).

• Sr. Associate Scientist I: BS in Biochemistry, Molecular Biology, Chemistry, Chemical Biology, or related field with 4+ years of industry experience, or Master’s with 2+ years of experience.
• Sr. Associate Scientist II: BS in Biochemistry, Molecular Biology, Chemistry, Chemical Biology, or related field with 6+ years of industry experience, or Master’s with 4+ years of experience.

Full‑time position based in Boulder, CO; in‑person lab work required.

$76,000 - $95,000, depending on experience and position level (Sr. Associate Scientist I or II)

Comprehensive benefits including health and dental insurance, disability and life insurance, 401(k) with company match, and bonus opportunities based on company and individual performance.