RMC1 (regulator of MON1-CCZ1) is a subunit of the CCZ1-MON1 Rab7 guanine exchange factor (GEF) complex that regulates endosomal and autophagic trafficking 1. As a positive regulator of CCZ1-MON1 function, RMC1 facilitates RAB7A recruitment to late endosomes and autophagosomes, promoting their maturation and lysosomal fusion 12. Structurally, RMC1 serves as an essential membrane recruitment factor for the GEF complex through electrostatic interactions with lipid membranes, distinguishing the metazoan tri-subunit complex from simpler dimeric fungal homologs 2. RMC1 deficiency impairs autophagic flux, causing accumulation of late endosome/autophagosome maturation regulators and reduced lysosomal content 1. Clinically, RMC1 dysfunction is implicated in endolysosomal trafficking defects affecting antibody-drug conjugate (ADC) toxicity in cancer cells 3. Additionally, genome-wide association studies identify RMC1 variants associated with dietary preferences and lipid metabolism, suggesting pleiotropic functions beyond autophagy 4. RMC1 thus represents a critical node integrating membrane trafficking, autophagy regulation, and metabolic homeostasis.