SH3YL1 is a phosphoinositide-binding protein that functions at the interface between plasma membrane and actin regulatory networks, coordinating cell membrane morphology with cytoskeletal dynamics 1. The protein contains a novel SYLF domain that binds phosphatidylinositol lipids (particularly PI(3,4,5)P3 and D5-phosphorylated phosphoinositides) and an SH3 domain 2. SH3YL1 regulates dorsal ruffle formation through phosphoinositide-dependent localization and interaction with SHIP2 phosphatase 2. Additionally, SH3YL1 mediates EGFR sorting into multivesicular bodies via interaction with ESCRT-I complex component Vps37B, controlling receptor degradation 3. In cancer biology, SH3YL1 cooperates with Dock4 to promote Rac1 activation and breast cancer cell migration 4. Clinically, SH3YL1 emerges as a promising biomarker across multiple diseases. Elevated plasma SH3YL1 associates with diabetic nephropathy in type 2 diabetes, correlating with albuminuria and blood pressure 5. DNA methylation variations in SH3YL1 are associated with myopia risk 6. In muscle-invasive bladder cancer, SH3YL1 expression correlates with NOX4 (r=0.62) and tumor invasiveness; low SH3YL1 predicts poor survival outcomes 7. Genome-wide association studies implicate SH3YL1 in kidney function and damage, supported by animal models 8.