PLEKHM1 (Pleckstrin Homology Domain-Containing Family M Member 1): PLEKHM1 is a protein involved in autophagy and lysosome function. It plays a key role in the fusion of autophagosomes with lysosomes, an important step in the autophagic process. Mutations in PLEKHM1 have been linked to osteopetrosis, a rare bone disorder.