What are the processes of pinocytosis?

The process of pinocytosis begins with the presence of the desired molecule in the extracellular fluid. The molecules, which act as inducers, bind to the cell membrane triggering the initiation of pinocytosis. These molecules can be ions, sugars, proteins or other molecules. As the cell membrane invaginates, it brings extracellular fluid along with the molecules into the cell. ATP is required since the solutes are being moved against their concentration gradient. Once the pouch is pinched off, the internalized vesicle buds off and moves into the cytoplasm. The material in pinocytotic vesicles fuse with a lysosome to be digested. In humans, pinocytosis is associated with the absorption of fat.