Final answer:
Carrier proteins that use energy to move substances against their concentration gradient in cells are often called "pumps." These include uniporters, symporters, and antiporters, which require ATP to operate and are crucial for processes such as nerve signal transmission.
Step-by-step explanation:
Carrier proteins are essential components of cellular membranes that facilitate the transport of substances across the membrane. When energy is used to move molecules against their concentration gradient, the process is known as active transport.
Carrier proteins in this context operate like pumps and are, therefore, often referred to as "pumps." These carrier proteins, such as uniporters, symporters, and antiporters, require energy typically in the form of ATP, to transport ions or molecules such as glucose, sodium, potassium, calcium, or hydrogen across the cell membrane.
One example is the Na+-K+ ATPase, which is an antiporter protein pump that carries sodium and potassium ions across the neuronal cell membranes to help transmit nerve impulses. Without these pumps, many vital cellular functions, including nerve signal transmission, would not be possible.