The PI3K (phosphatidylinositol 3-kinase) Class 3 antibody targets components of the Class III PI3K complex, primarily the catalytic subunit VPS34 (vacuolar protein sorting 34), encoded by the *PIK3C3* gene. Class III PI3K is distinct from Class I and II PI3Ks, as it exclusively generates phosphatidylinositol 3-phosphate (PtdIns3P), a lipid critical for membrane trafficking, autophagy, and lysosomal function. VPS34 forms a core complex with regulatory proteins like Beclin-1 and VPS15. which modulate its activity in autophagy initiation and endosomal sorting. Antibodies against PI3K Class III are essential tools for studying these processes, enabling detection of protein expression, localization, and interaction partners via techniques like Western blotting, immunofluorescence, and immunoprecipitation. Researchers use these antibodies to explore roles in diseases linked to autophagy dysregulation, such as cancer, neurodegenerative disorders, and metabolic conditions. For instance, reduced VPS34 or Beclin-1 levels are associated with impaired autophagy in Alzheimer’s or Parkinson’s disease models. Additionally, these antibodies help investigate crosstalk between autophagy and pathways like mTOR or apoptosis. Specificity validation (e.g., knockout controls) is crucial due to structural similarities among PI3K classes. Overall, PI3K Class III antibodies are pivotal in deciphering cellular homeostasis mechanisms and therapeutic targeting in autophagy-related pathologies.