Question

What name is given to the transmembrane proteins that allow this direct passage?

Answer 1

A membrane transport protein (or simply transporter) is a membrane protein[1] involved in the movement of ions, small molecules, and macromolecules, such as another protein, across a biological membrane. Transport proteins are integral transmembrane proteins; that is they exist permanently within and span the membrane across which they transport substances. The proteins may assist in the movement of substances by facilitated diffusion or active transport. The two main types of proteins involved in such transport are broadly categorized as either channels or carriers. The solute carriers and atypical SLCs[2] are secondary active or facilitative transporters in humans.[3][4] Collectively membrane transporters and channels are transportome. Transportomes govern cellular influx and efflux of not only ions and nutrients but drugs as well.