Rab effector protein involved in melanosome transport. Serves as link between melanosome-bound RAB27A and the motor protein MYO5A. Defects in MLPH are a cause of Griscelli syndrome type 3 (GS3). GS3 is a rare autosomal recessive disorder characterized by pigmentary dilution of the skin and hair, the presence of large clumps of pigment in hair shafts, and an accumulation of melanosomes in melanocytes, without other clinical manifestations. 3 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.