MREG (melanoregulin) is a cargo-recognition protein that functions in intracellular vesicle transport and organelle homeostasis. In melanocytes, MREG serves as a receptor for RILP and the RILP-DCTN1 complex on melanosomes, facilitating retrograde melanosome transport from the cell periphery to the center and thereby regulating hair pigmentation [UniProt annotation]. MREG requires cholesterol for function and binds various phosphatidylinositol lipids to mediate microtubule-dependent organellar transport. Beyond pigmentation, MREG is essential for normal phagosome maturation and lysosomal enzyme activation in retinal pigment epithelium cells, and contributes to degradation of the lipofuscin component A2E in the eye [UniProt annotation]. The protein localizes to late endosome membranes and organelle membranes where it regulates membrane fusion events. MREG overexpression causes accumulation of late endosomes and lysosomes at the microtubule organizing center. Clinically, dysregulation of MREG-mediated transport processes may contribute to vision loss and age-related ocular pathology through impaired clearance of photoreceptor disk membranes and lipofuscin accumulation. While the provided abstracts discuss 'Mreg' cells (regulatory macrophages), a distinct immunological entity, they do not address MREG gene function, indicating the need for additional immunological literature to clarify potential broader roles.