PDCD6IP (also known as ALIX) is a multifunctional ESCRT-associated protein central to membrane trafficking and cellular damage responses. Primary Function: PDCD6IP acts as a key coordinator of ESCRT-III machinery in intraluminal vesicle (ILV) formation and exosome biogenesis 1. It functions as an adaptor protein that recruits ESCRT-III components to endosomal membranes independently of canonical ESCRT-0/I/II pathways, promoting cargo sorting and delivery of tetraspanins to exosomes 1. Mechanism: PDCD6IP interacts with cargo adaptor proteins through LYPX(n)L motifs and SUMO-interacting motifs (SIMs), enabling selective protein packaging into extracellular vesicles 23. Upon lysosomal or endolysosomal damage, PDCD6IP is recruited via calcium signaling and coordinates membrane repair responses with autophagy 45. Disease Relevance: Mutations in PDCD6IP cause Microcephaly 29, highlighting its critical role in neural development. Additionally, PDCD6IP dysregulation promotes cancer metastasis through aberrant EV-mediated cargo delivery 3. Clinical Significance: PDCD6IP represents a potential therapeutic target for conditions involving membrane trafficking dysfunction, lysosomal pathology, and cancer progression. Its role in stress granule formation during lysosomal damage suggests relevance to viral infections and neurodegeneration 5.