Glycosylphosphatidylinositol anchoring signal

Characteristics

Encodes LENGGTSLSEKTVLLLVTPFLAAAWSLHP (29 amino acids, 87 nucleotides). The signal is cleaved at the omega site in the endoplasmic reticulum by the GPI transamidase, which forms an amide linkage between the phosphoethanolamine of a pre-formed GPI lipid and the new C terminus of the protein. The GPI core consists of a phosphatidylinositol lipid tail, a variable glycan core and the phosphoethanolamine linker, and mostly saturated acyl chains direct GPI-anchored proteins to lipid rafts. The mouse Thy-1-derived signal KDNTTLQEFATLAN places EGFP at the plasma membrane, Golgi membranes and secretory vesicles of mouse ES cells.

Applications: Displaying a protein on the outer surface of the plasma membrane, as a membrane-attached form of a protein that has an N-terminal signal peptide. With the mouse Thy-1-derived signal KDNTTLQEFATLAN, EGFP behind the acrosin signal sequence labels the plasma membrane in live mouse ES cells, embryos and tissues of transgenic mice, which are viable and fertile.

Limitations: Works only at the C terminus and only for a cargo that enters the secretory pathway, which needs an N-terminal signal peptide. The signal is cleaved on attachment. Anchored proteins can be released by GPI-specific phospholipases (types A2, C, D) and by membrane-proximal proteolysis. An uncleaved native Als5 signal (Candida albicans, in E. coli) alters conformation and reduces collagen IV binding.

References

1. Rhee et al. (2006). In vivo imaging and differential localization of lipid-modified GFP-variant fusions in embryonic stem cells and mice. Genesis - Rhee 2006 Lipid-Modified GFP
2. Borza et al. (2025). Unlocking the signaling potential of GPI-anchored proteins through lipolytic cleavage. Trends Cell Biol - Borza 2025 GPI-Anchored Protein Cleavage