In order for molecule X to cross the plasma membrane of a cell, it must first bind to an integral membrane protein. The binding of molecule X to the integral membrane protein immediately causes a conformational change to the integral membrane protein, which exposes molecule X to the other side of the membrane where it is then released. What is this an example of

Facilitated diffusion (passive transport)

Explanation

Facilitated diffusion is a type of passive transport mediated by transmembrane integral proteins that enable molecules and ions to move across biological membranes. Passive transport does not require energy (ATP) from the cell and occurs with a concentration gradient. Permeases are membrane transport proteins that bind to different substrates such as, for example, glucose, fructose and galactose. This binding triggers a conformational change in the transmembrane permease domains, thereby allowing substrate translocation across the membrane by passive transport.