Principal Scientist, Protein Engineering & Manufacturing

Exthymic•San Diego, CA

21d•$170,000 - $210,000

About The Position

Exthymic is an early-stage deep-tech startup focused on making curative cell therapies more widely accessible through patient-specific treatment manufacturing at the point of care. The company combines hardware, software, and biological engineering to develop its platform. The Principal Scientist, Protein Engineering & Manufacturing is the technical owner of protein reagents used in the company’s consumables. Reporting to the Chief Scientific Officer, this hands-on role sets protein strategy and determines whether reagents are produced internally or through partners, as well as how they are manufactured reproducibly at product scale and quality. The role guides a small group of scientists and research associates and works across teams to connect protein science with the company’s instrument and consumables. The position covers protein selection, engineering, discovery, optimization, expression, purification, labeling, conjugation, characterization, quality control, stability, and production scale-up. It also involves managing external discovery and manufacturing partners, protecting intellectual property, mentoring the team, collaborating across the platform, and contributing to invention disclosures and patent filings.

Requirements

Ph.D. in biochemistry, protein engineering, molecular biology, immunology, or a related field, plus 6 or more years of relevant industry experience, or equivalent.
Hands-on leadership of antibody or protein engineering programs from discovery or design through characterization.
Deep experience with recombinant protein expression, purification, and analytical characterization.
Experience with bioconjugation and labeling chemistries.
Track record of taking a protein reagent or biologic from development into reproducible production with defined specifications and quality control.
Experience managing CROs or external partners for antibody discovery, engineering, or production.
Experience guiding or mentoring scientists and research associates.
Comfort working in an early-stage startup with evolving priorities.

Nice To Haves

Experience with antibodies or protein reagents for diagnostics, cell selection, or cell-therapy applications.
Experience with protein immobilization on surfaces or biosensors.
Experience applying computational or AI-assisted protein design.
Familiarity with GMP or quality systems for reagents or biologics.

Responsibilities

Set the scientific strategy for proteins used in consumables, from selection and engineering through characterization.
Drive protein discovery, engineering, and optimization workflows, conducted in-house or with external partners.
Establish robust protein expression, purification, labeling, and conjugation methods, and scale them to supply the product.
Define protein specifications and analytical methods for identity, purity, activity, and stability, and drive lot-to-lot consistency.
Select and direct antibody-discovery, engineering, and protein-manufacturing partners; scope work, conduct diligence, and transfer methods while protecting intellectual property.
Mentor scientists and research associates and set standards for rigorous, well-documented work.
Collaborate with surface, cell, hardware, and software teams so protein reagents and assay readouts work together.
Identify inventions and contribute to disclosures and patent filings.