Transmembrane carrier proteins transport a wide array of ions and molecules by a process that involves conformational changes to mediate movement of the substrate in an energy-independent fashion. Carriers may be classed as passive (facilitated diffusion) transporters (uniporters), transporting a substrate down its electrochemical gradient, or secondary active transporters, coupling the transport of substrates against their electrochemical gradients with the transport of other substrates down their electrochemical gradients. Secondary active transporters may act as symporters, transporting substrates in the same direction, or antiporters, transporting substrates in opposite directions. The majority of transmembrane carrier proteins are classified as members of the Solute carrier (SLC) family. (Adapted from
PMID:31214990,
PMID:32810346,
FBrf0234984 and
FBrf0226917.)