The protein needed to move ions against their concentration gradient is known as Adenosine Triphosphate (or ATP for short).
Ions naturally have a tendency of moving down their concentration gradient. This kind of action is known as Passive Transport because there is no required energy. An example of this would be diffusion, which is a process where cells simply move down their concentration gradients.
When ions move against their concentration gradient, they use a protein called ATP for additional support in the process. This kind of action is called Active Transport because ATP is a necessity for the movement of ions. An example would be phagocytosis (a kind of endocytosis), which is a process of bacteria ingestion in which a cell “eats” or engulfs another.