APPL1 Gene: Function, Mutations, and Associated Diseases

The APPL1 gene encodes a multifunctional adaptor protein that contains an N-terminal Bin/Amphiphysin/Rvs (BAR) domain, a pleckstrin homology (PH) domain, and a C-terminal phosphotyrosine binding (PTB) domain. APPL1 is involved in signal transduction pathways, including insulin and adiponectin signaling, and plays roles in cell proliferation, apoptosis, and endosomal trafficking. Mutations in APPL1 are associated with maturity-onset diabetes of the young type 14 (MODY14).

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• Adiponectin signaling pathway

• Insulin signaling pathway

• PI3K-Akt signaling pathway

• Endocytosis

The APPL1 protein (UniProt Q9UKG1) is a 709-amino acid adaptor that localizes to endosomes and the plasma membrane. It contains an N-terminal BAR domain for membrane curvature sensing, a central PH domain for phosphoinositide binding, and a C-terminal PTB domain that interacts with phosphotyrosine motifs on receptors such as insulin receptor and adiponectin receptor. APPL1 mediates signal transduction by recruiting downstream effectors like AKT and Rab5, influencing cell survival, metabolism, and vesicle trafficking.