This is the molecular basis for the T-cell acute lymphoblastic leukemia (T-ALL) ribosomopathy. Left: "Crown view" of the large subunit of the ribosome highlighting critical functional parts. tRNAs pass through the accommodation corridor when traveling from outside the ribosome into the catalytic core (PTC). Right: Close-up view of ribosomal protein L10/uL16 and its surroundings. The mutations found in T-ALL patients are shown in yellow. These lie at the base of a loop (dotted lines) that protrudes into the accommodation corridor. When a tRNA passes through the accommodation corridor, it flips the loop up. This functions like a switch or a sensor, signaling to other regions of the ribosome that a tRNA has just passed through. In response, the ribosome undergoes a change in shape that allows it to proceed to the next step in the protein synthetic process. Mutations in the loop displace it, making it less able to do its job.