Transcellular Transport of Solutes

Transcellular transport is a cellular process that allows the movement of substances across polarized cells, such as endothelial and epithelial cells, with biochemically distinct membrane compositions on two opposite sides.

It is observed during nutrient absorption in the small intestine and selective transport of solutes across the blood-brain barrier.

For instance, the epithelial lining has a compact arrangement of cells. The tight junctions between these cells block solute movement between the cells.

So, solutes like monosaccharides, amino acids, and ions are transported across the cell with the help of membrane transport proteins present on the opposite sides of the cell.

Solutes can enter or leave the cell via three important ways, depending on the type of cell and the solute being transported.

Transcellular diffusion, where solutes such as glucose and fructose can diffuse from higher to lower concentrations.

Active transport, where solutes like calcium and copper ions are transported against their concentration gradient using energy from ATP hydrolysis.

Transcytosis, where solutes such as albumin, and lipoproteins are transported via vesicles across the cell.