biostudies-literatureUnknown637(8045)Pourmal SLytic cell death culminates in plasma membrane rupture, which releases large intracellular molecules to augment the inflammatory response. Plasma membrane rupture is mediated by the effector membrane protein ninjurin-1 (NINJ1)¹, which polymerizes and ruptures the membrane via its hydrophilic face^1-4. How NINJ1 is restrained under steady-state conditions to ensure cell survival remains unknown. Here we describe the molecular underpinnings of NINJ1 inhibition. Using cryogenic electron microscopy, we determined the structure of inactive-state mouse NINJ1 bound to the newly developed nanobody Nb538. Inactive NINJ1 forms a face-to-face homodimer by adopting a three-helix conformation with unkinked transmembrane helix 1 (TM1), in contrast to the four-helix TM1-kinked activeNature446-452https://www.ebi.ac.uk/biostudies/studies/S-EPMC11711097biostudies-literatureAutoinhibition of dimeric NINJ1 prevents plasma membrane rupture.PMC11711097Zhou LGupta SStowe IBRohou ANewton KAlegre KKayagaki NYang YJohnson MCZhang YChen PADixit VMPourmal STruong MEDeshpande IfalseAutoinhibition of dimeric NINJ1 prevents plasma membrane rupture.Lytic cell death culminates in plasma membrane rupture, which releases large intracellular molecules to augment the inflammatory response. Plasma membrane rupture is mediated by the effector membrane protein ninjurin-1 (NINJ1)¹, which polymerizes and ruptures the membrane via its hydrophilic face^1-4. How NINJ1 is restrained under steady-state conditions to ensure cell survival remains unknown. Here we describe the molecular underpinnings of NINJ1 inhibition. Using cryogenic electron microscopy, we determined the structure of inactive-state mouse NINJ1 bound to the newly developed nanobody Nb538. Inactive NINJ1 forms a face-to-face homodimer by adopting a three-helix conformation with unkinked transmembrane helix 1 (TM1), in contrast to the four-helix TM1-kinked active2025-01-01T00:00:00Z2025 Jan2026-06-02T08:05:03.225Z2026-04-16T03:10:42.185ZS-EPMC117110973947686310.1038/s41586-024-08273-4