GPCR kinases generate an APH1A phosphorylation barcode to regulate amyloid-D generation

Emerging evidence suggests that G protein-coupled receptor (GPCR) kinases (GRKs) are associated with the pathophysiology of Alzheimer's disease (AD). However, GRKs have not been directly implicated in regulation of the amyloid-D (AD) pathogenic cascade in AD. Here, we determine that GRKs phosphorylate a non -canon-ical substrate, anterior pharynx-defective 1A (APH1A), an integral component of the y-secretase complex. Significantly, we show that GRKs generate distinct phosphorylation barcodes in intracellular loop 2 (ICL2) and the C terminus of APH1A, which differentially regulate recruitment of the scaffolding protein D-arrestin 2 (Darr2) to APH1A and y-secretase-mediated AD generation. Further molecular dynamics simulation studies reveal an interaction between the Darr2 finger loop domain and ICL2 and ICL3 of APH1A, similar to a GPCR-D-arrestin complex, which regulates y-secretase activity. Collectively, these studies provide insight into the molecular and structural determinants of the APH1A-Darr2 interaction that critically regulate AD generation.