Mina Hirata, Maho Fujino, Kazuya Ichihara, Ronghao Tang, Momoko Narita, Wakana Iwasaki, Chisa Shiraishi, Taichi Shiraishi, Atsushi Hatano, Toru Suzuki, Tokichiro Abe, Tomoyo Takami, Emi Mishiro-Sato, Atsushi Toyoda, Masaki Matsumoto, Yoshikazu Tanaka, Takuhiro Ito, Toshifumi Inada, Keiichi I Nakayama, Takeshi Yokoyama, Akinobu Matsumoto
Ribosomal protein L41 (RPL41 or eL41) is the smallest ribosomal protein and forms the eukaryote-specific bridge, eB14, near the decoding center; however, its role in mammalian translation remains unclear. In this study, we established RPL41-deficient models of human HEK293T cells and mice to define its function. Cryo-electron microscopy revealed that RPL41 constrains intersubunit conformational dynamics without inducing major local static rearrangements. Loss of RPL41 altered A-site dynamics, slowed elongation, modestly increased amino acid misincorporation, and modestly enhanced readthrough of collision-inducing reporter sequences. Quantitative proteomic analysis suggested that these translational defects compromise long-protein homeostasis, as evidenced by increased insolubility and reduced abundance of long proteins. In vivo, Rpl41-/- mice were viable but exhibited growth retardation and decreased abundance of long proteins in tissues. Our findings reveal a conserved role for RPL41 in maintaining ribosome dynamics and translational fidelity, indicating that RPL41 supports ribosome function and long-protein homeostasis in mammals.