AsialoglycoproteinRezeptor

Asialoglycoprotein receptor (ASGPR) is a transmembrane protein found on the surface of hepatocytes, the main functional cells of the liver. It plays a crucial role in the endocytosis of glycoproteins that have had their terminal sialic acid residues removed. This desialylation exposes underlying galactose or N-acetylgalactosamine residues, which are then recognized and bound by the ASGPR. This recognition mechanism is highly specific, allowing the receptor to selectively internalize these modified proteins.

The ASGPR is a heterotrimer composed of three subunits, typically H1, H2, and H3. These subunits assemble to form a functional receptor complex. The binding of ligands to the ASGPR triggers internalization of the receptor-ligand complex into the cell via endocytosis. Once inside the hepatocyte, the ASGPR can release its cargo within endosomes, and the receptor itself is often recycled back to the cell surface to participate in further rounds of ligand binding.

This receptor-mediated endocytosis pathway mediated by ASGPR is essential for the clearance of certain endogenous glycoproteins from the circulation, such as certain enzymes and hormones that have undergone desialylation. Furthermore, the ASGPR has become an important target for drug delivery. Its presence on hepatocytes makes it an attractive target for delivering therapeutic agents specifically to the liver. This targeted delivery can improve drug efficacy and reduce systemic toxicity. Research continues to explore the full spectrum of ASGPR function and its therapeutic potential.