CTNNA3 (catenin alpha 3) encodes α-T-catenin, a critical component of the cardiomyocyte intercalated disc that mediates stretch-resistant cell-cell adhesion 1. The protein functions as a bridge between cadherin-based adhesion complexes and the actin cytoskeleton, providing mechanical linkage essential for cardiac tissue integrity 2. CTNNA3 is predominantly expressed in cardiomyocytes and regulates cardiac conduction and action potential duration 3. Phosphorylation of CTNNA3 at specific residues is crucial for maintaining its localization at the intercalated disc and regulating cell-cell conductance 1. Fortilin protects CTNNA3 from phosphorylation-induced ubiquitination and proteasomal degradation, thereby suppressing apoptosis 4. Beyond cardiac function, CTNNA3 acts as a tumor suppressor in hepatocellular carcinoma by inhibiting proliferation and invasion through Akt signal suppression 5. Clinically, CTNNA3 is implicated in arrhythmogenic disorders: rare structural variants (deletions) associate with atrial fibrillation risk 3, and phosphorylation abnormalities contribute to dilated cardiomyopathy pathophysiology 1. Copy number variations in CTNNA3 are also associated with pediatric food allergy susceptibility 6. These findings establish CTNNA3 as a multifunctional protein with critical roles in cardiac homeostasis and cellular protection mechanisms.