Are responsible for the transport of substance down concentration gradient during facilitated diffusion

The membrane proteins are the ones responsible for the transport of the substance down concentration gradient during facilitated diffusion. In facilitated diffusion, materials diffuse or scatter across the plasma membrane with the assistance of the membrane proteins. The concentration gradient allows these materials to diffuse provided it will not use its cellular energy in doing so. Some facilitated proteins protect these materials not to be affected by the force of the membrane. The material that is being transported using the facilitated diffusion has to pass several channels before it reaches its destination.