Channel proteins are specialized proteins embedded in cell membranes that facilitate the movement of ions and molecules across the membrane. They create pathways that allow specific substances, such as sodium ions or potassium ions, to pass through, which is essential for various cellular functions, including nerve signal transmission and muscle contraction. These proteins are selective, meaning they only allow certain substances to enter or exit the cell, maintaining the cell's internal environment. Channel proteins can be gated, opening or closing in response to specific signals, which helps regulate the flow of materials in response to the cell's needs.