Protein targeting is the process by which proteins are directed to specific locations within or outside of a cell. This ensures that proteins reach their functional destinations, such as the nucleus, mitochondria, or the cell membrane, where they perform essential roles. Proteins contain specific sequences of amino acids, known as signal peptides, that act like addresses, guiding them to their correct locations. Once the protein reaches its destination, it can carry out its functions, such as catalyzing reactions or facilitating communication between cells, which are vital for maintaining cellular health and function.