Lipoproteins (post-translational modification)
Lipoproteins are special proteins that are found in all living things and viruses except archaea . Their peculiarity is that they are covalently bound to a lipid at the N terminus of the protein , which means that the protein usually becomes fat-soluble or can be anchored in a plasma membrane . A corresponding number of lipoproteins are therefore membrane proteins . In 2010, over 71,000 proteins with this modification were known in the central protein database UniProt in all living beings.
The protein is bound to either a glycolipid , a glycerolipid , or a fatty acid such as farnesylate or myristate . This change is a post-translational modification , that is, it takes place after the translation of the protein with the help of special enzymes .
The classification is based on the bound lipid, the most common are:
- Proteins with GPI anchors in eukaryotes
- Proteins with a GPI-like anchor in which a similarly complex oligoglycan is linked to a sphingolipid-inositol unit; also only in eukaryotes
- bacterial proteins, in which a cysteine via its thiol group as a thioester with 1,2-diacylglycerols is connected
- Myristoyl proteins found in eukaryotes and their viruses; they are not tied to the membrane
- Palmitoyl proteins in bacteria and eukaryotes
- prenylated proteins in eukaryotes and viruses; Farnesylated proteins are a special case
literature
- Hayashi S, Wu HC: Lipoproteins in bacteria . In: J. Bioenerg. Biomembrane . 22, No. 3, June 1990, pp. 451-71. PMID 2202727 .