In this episode of BioBits &Bytes, we decode how cells rewrite the behavior of proteins after translation through posttranslational modifications (PTMs)—tiny changes that can mean the difference between function and dysfunction. Focusing on polyglutamine (polyQ) diseases like Huntington’s disease, we explore how modifications such as phosphorylation, ubiquitination, and SUMOylation influence the aggregation, toxicity, and fate of proteins with expanded CAG repeats. This molecular fine-tuning not only drives disease progression but also opens new doors for therapeutic targeting.