Cellular gatekeepers.
D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D002468:Cell Physiological Phenomena; D005057:Eukaryotic Cells / Q000166:cytology* / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism*; D011387:Prokaryotic Cells / Q000166:cytology* / Q000502:physiology
D008565:Membrane Proteins