What does cotransporter mean?
A cotransporter is a type of membrane protein that moves two or more different molecules or ions across a cell membrane at the same time, typically in the same direction. Rather than consuming ATP directly, most cotransporters exploit the electrochemical gradient of one solute—often sodium or a proton—as the energy source to pull a second substance along with it, a mechanism known as secondary active transport. A familiar example is the sodium–glucose cotransporter found in the small intestine and kidney, which enables the body to absorb and retain glucose efficiently. The term appears chiefly in biochemistry, physiology, and pharmacology: drugs such as SGLT2 inhibitors act by blocking specific cotransporters. Related terms include symporter, which specifies same-direction transport, and antiporter, which describes opposite-direction exchange. For students of biology and medicine, understanding cotransporters is essential to grasping how cells absorb nutrients, regulate ion balance, and maintain homeostasis.
nounA membrane protein that transports two or more different substances across a cell membrane at the same time, usually in the same direction, using the concentration gradient of one substance to drive the movement of the other. Cotransporters are also called symporters when both substances move in the same direction.
- A membrane protein that couples the simultaneous transport of two or more solutes across a cell membrane in the same direction, harnessing the electrochemical gradient of one solute to drive the transport of another.
"The sodium–glucose cotransporter in the intestinal lining allows cells to absorb glucose even against its concentration gradient."
"Inhibiting the sodium–glucose cotransporter SGLT2 increases glucose excretion in the urine, lowering blood sugar in diabetics."
"The plant's nutrient uptake depends on proton-coupled cotransporters embedded in the root cell membranes."
Standard regular plural; commonly pluralized when discussing families or classes of these proteins.
"Several cotransporters in the kidney's proximal tubule reclaim filtered nutrients from the urine."
Your gut absorbs glucose against all odds thanks to a cotransporter that hitchhikes it on sodium's downhill ride into the cell.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cotransporter
The word combines the prefix 'co-', from Latin meaning 'together', with 'transporter', derived from Latin 'trans' ('across') and 'portare' ('to carry'). It arose in twentieth-century scientific English as cell biologists characterized proteins that carry multiple substrates simultaneously across membranes. Its roots are shared with everyday words such as 'transport', 'portable', and 'cooperate'.
Related word forms
How cotransporter is actually used
A technical term used almost exclusively in biochemistry, cell biology, and physiology; it does not appear in general conversation or non-scientific writing. Strictly speaking, 'cotransporter' covers symporters (same direction) but is sometimes loosely extended to include antiporters, which move substrates in opposite directions.
Easily confused with cotransporter
An antiporter moves two substances across the membrane in opposite directions, whereas a cotransporter (symporter) moves them in the same direction.