ליפידים כעוגנים

The three most common types of lipid anchors are prenyl groups, fatty acyl groups, and glycosylphosphatidylinositol or GPI anchors.

The prenyl groups are the 15 carbon farnesyl and the 20 carbon geranylgeranyl groups. They bond to cysteine residues at or near the carboxy terminus of proteins.  

Saturated 14 carbon myristic acid and the 16 carbon palmitic acid are the most common fatty acyl anchors linked to proteins.

The addition of myristic acid, or myristoylation, happens at a protein's N-terminal glycine residue. Palmitoylation of the proteins can occur at the N- or C- terminal cysteine residue.

Prenylated, myristoylated, and palmitoylated proteins play an essential role in intracellular signaling pathways and protein-protein interactions.

GPI anchors attach to extracellular proteins and contain a core structure of phosphatidylinositol, glucosamine, three mannoses, and phosphoethanolamine.

The phosphoethanolamine bonds to the C-terminal amino acid of the target protein, and the phospholipid inserts itself into the outer layer of the membrane.

This allows GPI anchored proteins to participate in extracellular functions such as cell-cell communication and cell adhesion.