Receptor-mediated Uptake of Lysosomal Enzymes

This paper reviews the evidence for two different forms of carbohydrate-mediated recognition of lysosomal enzymes by cell surface receptors. The recognition marker on lysosomal enzymes which are rapidly pinocytosed by fibroblasts contains phosphate, probably linked to D-mannose as a phosphomannosyl moiety. The fraction of lysosomal hydrolases bearing this recognition marker for fibroblasts varies, depending on the tissue source. Another form of recognition accounts for rapid plasma clearance of infused lysosomal enzymes in the rat. This rapid clearance is mediated by receptors on Kupffer cells and other reticuloendothelial cells that recognize mannosyl residues on the glycoprotein hydrolases.