Essential amino acids such as leucine activate mTORC1 signalling after entering the lysosome, but the molecular basis for lysosomal amino-acid uptake is unclear. Here Milkereit et al. show that LAPTM4b, a lysosomal membrane protein, recruits a leucine transporter to the lysosome and promotes amino-acid influx and mTORC1 signalling.
- Ruth Milkereit
- Avinash Persaud
- Daniela Rotin