Senior Scientist I

Job Description Position Summary We are seeking a highly motivated Senior Scientist to join our Protein Expression and Purification group at our South San Francisco site. The successful candidate will play a crucial role in the discovery of novel therapeutics through design and execution of biologics and protein expression activities with a primary focus on mammalian systems. The successful candidate will bring deep expertise in recombinant biologics production including monoclonal antibodies, multispecific scaffold and novel protein modalities particularly in CHO and HEK293 systems and will contribute to advancing discovery-stage biologics programs. Key Responsibilities Design, execute, and optimize recombinant protein expression workflows in mammalian systems (e.g., CHO, HEK293), including transient and stable expression. Develop and implement strategies to improve protein yield, quality, and scalability for biologics production. Represent the Protein Design and Production group in project team meetings and propose the best path forward, contribute to decision making processes and coordinate efforts with stakeholders. Contribute to DNA construct design, including vector design, cloning strategies, and sequence optimization. Work with CRO to coordinate outsourcing production activities. Collaborate with cross‑functional teams (protein purification, analytics, discovery teams) to deliver high‑quality biologics. Evaluate and introduce new technologies to enhance efficiency of protein expression platforms. Troubleshoot complex expression challenges and propose innovative solutions. Maintain accurate documentation of experiments and communicate results effectively to stakeholders. Ensure compliance with safety protocols and maintain a clean and organized laboratory environment. Collaborate effectively with a group of scientists and demonstrate inclusive behaviors to drive our core mission. Desired Experience and Skills Extensive hands‑on experience in recombinant protein and biologics expression in mammalian systems. Strong knowledge of cell culture, transfection, process development and cell line development strategies. Solid background in molecular biology, including construct design, cloning, and plasmid engineering. Experience working with antibody and complex biologics, bispecifics, fusion proteins. Commitment to maintaining accurate and timely records in Electronic Laboratory Notebooks (ELN) and databases. Strong problem‑solving skills and ability to work in a fast‑paced environment. Excellent communication and collaboration skills. Preferred Skills Experience with protein production in bioreactors is a plus but not required. Knowledge of protein purification and characterization techniques. Experience with bioinformatics tools for sequence analysis and construct design. Education Requirements PhD in Molecular Biology, Cell Biology, Biochemistry, or a related discipline with 3+ years of relevant experience (industry preferred); or MS with 4+ years / BS with 7+ years of significant industry experience. Required Skills Cell Cultures Cross‑Functional Collaboration Detail‑Oriented High‑Throughput Screening Laboratory Documentation Mammalian Cell Culture Molecular Biology Techniques Primary Cell Culture Protein Expression Protein Purifications Recombinant Protein Expression Results‑Oriented Safety Protocols Safety Standards US and Puerto Rico Residents Only Our company is committed to inclusion, ensuring that candidates can engage in a hiring process that exhibits their true capabilities. If you need an accommodation during the application or hiring process, let us know. Equal Employment Opportunity As an Equal Employment Opportunity Employer, we provide equal opportunities to all employees and applicants for employment and prohibit discrimination on the basis of race, color, age, religion, sex, sexual orientation, gender identity, national origin, protected veteran status, disability status, or other applicable legally protected characteristics. As a federal contractor, we comply with all affirmative action requirements for protected veterans and individuals with disabilities. For more information about personal rights under the U.S. Equal Opportunity Employment laws, visit: EEOC Know Your Rights, EEOC GINA Supplement, and Learn more about your rights, including under California, Colorado, and other US State Acts. The salary range for this role is $131,400.00 - $206,800.00. This is the lowest to highest salary we in good faith believe we would pay for this role at the time of this posting. An employee’s position within the salary range will be based on several factors including, but not limited to relevant education, qualifications, certifications, experience, skills, geographic location, government requirements, and business or organizational needs. The successful candidate will be eligible for annual bonus and long‑term incentive, if applicable. We offer a comprehensive package of benefits. Available benefits include medical, dental, vision healthcare and other insurance benefits (for employee and family), retirement benefits, including 401(k), paid holidays, vacation, and compassionate and sick days. Application deadline for this position is stated on this posting. Current Employees apply HERE. Current Contingent Workers apply HERE. San Francisco Residents Only We will consider qualified applicants with arrest and conviction records for employment in compliance with the San Francisco Fair Chance Ordinance. Los Angeles Residents Only We will consider for employment all qualified applicants, including those with criminal histories, in a manner consistent with the requirements of applicable state and local laws, including the City of Los Angeles’ Fair Chance Initiative for Hiring Ordinance. Search Firm Representatives Please Read Carefully Merck & Co., Inc., Rahway, NJ, USA, also known as Merck Sharp & Dohme LLC, does not accept unsolicited assistance from search firms for employment opportunities. All CVs / resumes submitted by search firms to any employee at our company without a valid written search agreement for this position will be deemed the sole property of our company. No fee will be paid in the event a candidate is hired by our company as a result of an agency referral where no pre‑existing agreement is in place. Where agency agreements are in place, introductions are position specific. Please, no phone calls or emails. Employee Status: Regular Relocation: Domestic VISA Sponsorship: Yes Travel Requirements: 10% Flexible Work Arrangements: Not Applicable Shift: 1st - Day Valid Driving License: No Hazardous Material(s): N/A Job Posting End Date: 08/7/2026 *A job posting is effective until 11:59:59 PM on the day BEFORE the listed job posting end date. Please ensure you apply to a job posting no later than the day BEFORE the job posting end date. #J-18808-Ljbffr EyeBio