HEPARIN, SULFATED HEPARINOIDS, AND LIPOTEICHOIC ACIDS BIND TO THE 70-KDA PEPTIDOGLYCAN LIPOPOLYSACCHARIDE RECEPTOR PROTEIN ON LYMPHOCYTES

The same 70-kDa protein, present on the surface of mouse lymphocytes, served as the predominant binding site for heparin, heparinoids, and b acterial lipoteichoic acids, as well as peptidoglycan and lipopolysacc harides. This conclusion was supported by the following results: (a) a ll of these compounds photoaffinity cross-linked to one major 70-kDa 6 .5-7.0 pI protein that co-migrated on two-dimensional polyacrylamide g el electrophoresis; (b) peptide maps of the 70-kDa proteins digested w ith chymotrypsin, subtilisin, protease V, or papain yielded the same p eptides for heparin-, lipoteichoic acid-, peptidoglycan-, and lipopoly saccharide-binding proteins; (c) cross-linking of peptidoglycan, lipop olysaccharide, lipoteichoic acid, and heparin was competitively inhibi ted by the same compounds with the same order of potency, i.e. carboxy l-reduced sulfated heparin > peptidoglycan > pentosan polysulfate > he parin > chitin > dextran sulfate > trestatin sulfate > polyanetholesul fonate > fucoidan> beta-cyclodextrin tetradecasulfate > heparan sulfat e > carrageenan lambda > lipoteichoic acids > Re-lipopolysaccharide > lipopolysaccharide > lipid A > polygalacturonic acid; and (d) cross-li nking of each of these ligands was not inhibited by carboxyl-reduced h eparin, dextran, beta-cyclodextrin, trestatin, carrageenan kappa, chon droitin 4-sulfate, chondroitin 6-sulfate, beta-D-glucan, carboxymethyl cellulose, levan, alpha-D-mannan, and glycogen. The minimum size of th e molecule that bound was 7-9 glycan residues, whereas, di- and trisac charides did not bind. There was a logarithmic linear relationship bet ween the strength of the binding and the length of the polymer (up to >1500 glycan residues), which indicates an avidity effect of the coope rative binding of one polymeric molecule to several receptor molecules on the cell surface. The 70-kDa receptor, therefore, has a broad, but limited specificity of binding for non-charged (peptidoglycan and chi tin), highly negatively charged (heparin and heparinoids), and weakly negatively charged (lipoteichoic acids, lipopolysaccharides, and lipid A) ligands.