Channel proteins

Channel proteins, one of the two classes of membrane transport proteins, allow specific solutes to passively traverse lipid bilayers through an aqueous pore. Most solutes that pass through channel proteins have a specified molecular weight and charge and are inorganic ions. The concentration and electrical gradients of charged ions determines the direction of flow of the ions through the membrane: they move from an area of high to low concentration in processes known as either passive transport or facilitated diffusion. The movement of ions through transporters, the other class of membrane transport proteins, is mediated in contrast to channel proteins either actively or passively. (Alberts, 2008,et al., 653)