N-Acylneuraminate-9-phosphates are a class of glycosylphosphatidyl inositol (GPI) anchor precursors, playing pivotal roles in the biosynthesis of GPI anchors in eukaryotic cells. These compounds consist of an N-acetyl neuraminic acid residue attached to a phosphate group via position 9 of the sugar moiety. The presence of an acyl chain further diversifies their structure and biological activities. They serve as key intermediates for the assembly of GPI-anchored proteins, which are essential for cell signaling, adhesion, and immune modulation. N-Acylneuraminate-9-phosphates are synthesized in the endoplasmic reticulum (ER) and then trafficked to the plasma membrane where they undergo further processing by phosphatidylinositol mannosyltransferases to form mature GPI anchors. Their structural complexity and functional diversity make them critical components in various biological processes, including cell signaling pathways and host-pathogen interactions.