APPL2 (adaptor protein, phosphotyrosine interacting with PH domain and leucine zipper 2) is a multifunctional scaffolding protein that regulates diverse cellular processes through protein-protein interactions and membrane targeting. The protein contains BAR, PH, and PTB domains that enable oligomerization with APPL1, membrane binding, and phosphoinositide interactions 1. APPL2 functions as a dynamic scaffold on RAB5-associated endosomal membranes, where it undergoes movement, fusion, and fission events 1. In metabolic regulation, APPL2 acts as a negative regulator of adiponectin signaling by competitively inhibiting APPL1, contributing to adiponectin resistance in obesity 23. Conversely, in pancreatic β-cells, APPL2 enhances glucose-stimulated insulin secretion by promoting F-actin remodeling through interaction with RacGAP1, which suppresses its negative regulation of Rac1 activity 4. APPL2 also forms distinct signaling complexes with various receptors, including interactions with FSHR independently of APPL1, suggesting specialized scaffolding functions 5. Additionally, APPL2 expression is regulated by long non-coding RNAs and contributes to cell migration in pathological conditions such as rheumatoid arthritis 6. The protein's expression levels are also altered in breast cancer, where downregulation correlates with disease progression 7.