<p><strong><span data-contrast="auto">What if…</span></strong><span data-contrast="auto"> you could join an organization that creates, resources, and builds life sciences companies that invent breakthrough technologies in order to transform health care and sustainability?</span><span data-ccp-props="{"134233117":true,"134233118":true}"> </span></p> <p><span data-contrast="auto">Flagship Labs 129 (FL129) is an early-stage biotechnology startup with an ambitious and exciting mission: to unlock the future of small molecule drug discovery. FL129 is developing a revolutionary approach to this challenge and is recruiting a team of top-tier scientists to build this powerful and first-in-category platform. This is a unique opportunity to be one of the first employees of a biotech startup that combines an innovative mindset with the resources and know-how of Flagship Pioneering. This is a hands-on role with substantial ownership for a scientist who is excited to set technical direction from day one and, over time, help build the team.</span><span data-ccp-props="{"134233117":true,"134233118":true}"> </span></p> <p><strong><span data-contrast="auto">Position Summary:</span></strong><span data-ccp-props="{"134233117":true,"134233118":true}"> </span></p> <p><span data-contrast="auto">We are seeking a motivated and highly collaborative Senior Scientist to join FL129's growing team of experimental and computational scientists building a novel platform technology. The successful candidate will design, construct, and functionally interrogate large protein variant libraries — linking variant genotype to measured phenotype at scale — and will help translate those readouts into data products that drive the platform. This role is among the first hires, affording the opportunity to shape and influence the company's scientific direction and team culture.</span><span data-ccp-props="{"134233117":true,"134233118":true}"> </span></p> <p><span data-contrast="auto">We welcome candidates from a range of adjacent backgrounds — deep mutational scanning, directed evolution, antibody or protein display engineering, massively parallel reporter assays (MPRA), or pooled genetic screens — who have the core library-building and selection skills below and are energized by applying them to a new problem.</span><span data-ccp-props="{"134233117":true,"134233118":true}"> </span></p> <p><strong><span data-contrast="auto">Key Responsibilities:</span></strong><span data-ccp-props="{"134233117":true,"134233118":true}"> </span></p> <ul> <li data-leveltext="•" data-font="" data-listid="5" data-list-defn-props="{"335552541":1,"335559685":460,"335559991":260,"469769242":[8226],"469777803":"left","469777804":"•","469777815":"hybridMultilevel"}" data-aria-posinset="1" data-aria-level="1"><span data-contrast="auto">Set technical direction for library design and functional interrogation, aligned with FL129's core strategic goals, and influence the company's broader scientific strategy as an early hire.</span><span data-ccp-props="{"134233279":false,"335559739":80}"> </span></li> </ul> <ul> <li data-leveltext="•" data-font="" data-listid="5" data-list-defn-props="{"335552541":1,"335559685":460,"335559991":260,"469769242":[8226],"469777803":"left","469777804":"•","469777815":"hybridMultilevel"}" data-aria-posinset="2" data-aria-level="1"><span data-contrast="auto">Design, construct, and experimentally test large-scale protein variant libraries, including deep mutational scanning and related saturation mutagenesis approaches.</span><span data-ccp-props="{"134233279":false,"335559739":80}"> </span></li> </ul> <ul> <li data-leveltext="•" data-font="" data-listid="5" data-list-defn-props="{"335552541":1,"335559685":460,"335559991":260,"469769242":[8226],"469777803":"left","469777804":"•","469777815":"hybridMultilevel"}" data-aria-posinset="3" data-aria-level="1"><span data-contrast="auto">Establish and optimize display, selection, and sorting workflows that link protein genotype to measured phenotype.</span><span data-ccp-props="{"134233279":false,"335559739":80}"> </span></li> </ul> <ul> <li data-leveltext="•" data-font="" data-listid="5" data-list-defn-props="{"335552541":1,"335559685":460,"335559991":260,"469769242":[8226],"469777803":"left","469777804":"•","469777815":"hybridMultilevel"}" data-aria-posinset="4" data-aria-level="1"><span data-contrast="auto">Assess library quality and variant coverage and validate outputs through biochemical and biophysical characterization of purified proteins.</span><span data-ccp-props="{"134233279":false,"335559739":80}"> </span></li> </ul> <ul> <li data-leveltext="•" data-font="" data-listid="5" data-list-defn-props="{"335552541":1,"335559685":460,"335559991":260,"469769242":[8226],"469777803":"left","469777804":"•","469777815":"hybridMultilevel"}" data-aria-posinset="5" data-aria-level="1"><span data-contrast="auto">Build and evolve the protein-engineering function: optimize workflows and establish best experimental and documentation practices to enable platform excellence.</span><span data-ccp-props="{"134233279":false,"335559739":80}"> </span></li> </ul> <ul> <li data-leveltext="•" data-font="" data-listid="5" data-list-defn-props="{"335552541":1,"335559685":460,"335559991":260,"469769242":[8226],"469777803":"left","469777804":"•","469777815":"hybridMultilevel"}" data-aria-posinset="6" data-aria-level="1"><span data-contrast="auto">Par