cotransporter

This term is a specialized technical noun used almost exclusively within biochemistry, cell biology, and pharmacology. It describes a specific mechanism of secondary active transport where the movement of one solute down its electrochemical gradient provides the energy to move another solute against its gradient.

In a professional scientific register, it is often contrasted with symporters (which are functionally identical) and antiporters (which move solutes in opposite directions). Because it refers to a physical protein structure, it is treated as a standard countable noun in academic literature.