Fig. 2

Representations of the proteolipid code. a Structure of a zone resolved by cryogenic electron microscopy containing the Slo1 channel α tetramer [14] (PDB ID: 8GHF, silver ribbons) and interacting β4 subunit [15] (PDB ID: 6V22, light green). The channel has fingerprints of cholesterol (green) and PC (blue) [14], recognizes PI(4,5)P₂ via basic (orange and red) and aromatic (yellow) residues [16,17,18], and is regulated by Ca²⁺ (magenta spheres) and coordinates Mg²⁺ (aqua). Created with ICM-browser. For a model to be called a zone, it should contain a set of molecules capable of performing a biological function in a membrane. b The lipidome depicted with hexagons representing individual molecules with their standard IUPAC abbreviations and organized by their major but nonexclusive subcellular origin [19, 20]. PIP terminal phosphate numbers are displayed on red corners and arrows indicate enzymatic reactions that convert these lipids. c Eukaryotic organelles are depicted and coloured as in b. Lipid aliphatic chains have different lengths and degrees of unsaturation which vary by zone. d The biological code composed of the genetic and proteolipid codes