Protein folding and post-translational modifications

Welcome to this lecture on protein folding and post translational modifications, providing an overview of the principles of protein folding, including how amino acid sequences determine structure and function and the role of molecular chaperones in ensuring proper folding. We will also explore post translational modifications such as phosphorylation and glycosylation, highlighting their impact on protein behavior and regulation. Finally, we'll discuss how the interplay between folding, modifications and cellular quality control maintains homeostasis and how disruptions in these processes can contribute to disease. Proteins begin as linear amino acid chains, but their biological roles depend on forming specific three dimensional shapes, known as the native state. These shapes are dictated by the amino acid sequence, which guides protein folding. Hydrophobic residues usually end up inside the protein, while hydrophilic ones face outward interacting with water. Correct folding is crucial for function, localization, stability, and preventing harmful aggregates, making it tightly regulated in cells. While the amino acid sequence contains folding instructions, the crowded and dynamic cellular environment makes spontaneous folding risky. Molecular chaperones are specialized proteins that prevent nascent or stress denatured polypeptides from following non productive folding pathways and aggregating. Chaperones like HSP 70 and chaperonins recognize exposed hydrophobic segments