Cytoplasmic polyadenylation element-binding protein 3 (CPEB3) is an RNA-binding protein that is essential for long-term memory formation. Its N-terminal intrinsically disordered region (residues 1–459) exhibits high aggregation propensity and regulates the translation of specific mRNAs, including those encoding AMPA receptor subunits, through processes such as liquid–liquid phase separation and the formation of fibrillar structures. However, the molecular basis of these regulatory mechanisms remains poorly understood. In this study, we present the backbone resonance assignments of three segments within the intrinsically disordered region of CPEB3 (residues 1–120, 186–315, and 400–459). In agreement with sequence-based secondary structure predictions, the 1–120 and 400–459 segments were disordered, whereas the 186–315 segment formed a partial α-helix.