PDCD6 (programmed cell death 6) is an evolutionarily conserved calcium-binding protein with multifaceted cellular functions across different subcellular compartments 1. The protein serves as a critical regulator of vesicular transport, specifically participating in COPII vesicle-dependent endoplasmic reticulum-to-Golgi transport 1. PDCD6 functions through calcium-dependent mechanisms, with its partner PDCD6IP/ALIX forming complexes that respond to calcium signals from damaged lysosomes 2. In stress responses, PDCD6 helps protect lysosomal membrane integrity through ESCRT-mediated mechanisms when calcium is released during osmotic stress 3. The protein also regulates innate immunity by negatively controlling LC3-associated phagocytosis through interaction with lactate dehydrogenase A (LDHA), modulating lactate metabolism and RUBCN lactylation 4. Additionally, PDCD6 participates in nutrient stress responses, where it contributes to lysosome-dependent microautophagy of ER exit sites along with ALG2 and ESCRT proteins 5. Clinically, PDCD6 shows disease relevance in cancer, where genetic polymorphisms are associated with cancer risk 6, and its expression correlates with angiogenesis regulation in prostate cancer 7. The protein's diverse roles in membrane dynamics, stress responses, and cellular homeostasis make it a significant target for therapeutic development.