Passive transporter, is a protein intergral within the membrane that allows ions or molecules to pass through the membrane without using energy/ATP. The molecule or ion will move down it's concentration gradient by facillitated diffusion. Each transporter is usually only specific to one molecule or a group of molecules with similar structures.
- ↑ B.Alberts et al. (2008) Molecular Biology of the Cell, 5th Edition, NewYork:Garland Science, Taylor &amp; Francis Group, Chapter 11, Page 652