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pubmed:abstractText |
We have identified a receptor for colonization factor antigen I (CFA/I) pili in human erythrocyte membranes. Erythrocyte binding assays, using whole organisms, suggested that the CFA/I receptor was a glycoprotein containing important sialic acid moieties. Subsequently, human erythrocyte membranes were extracted with lithium diiodosalicylate to obtain a soluble glycoprotein fraction from which to isolate receptors. The extracted material caused agglutination of the CFA/I+ but not the CFA/I- organisms at a protein concentration of 0.5 mg/ml. The CFA/I receptor was identified in iodinated extract by an affinity isolation procedure, using whole bacterial cells. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography of the washed, extract-coated H10407 CFA/I+ organisms revealed a band with an apparent molecular weight of 26,000 which was present in the original extract but was not observed on extract-coated H10407 CFA/I- bacteria. The addition of purified CFA/I pili reduced binding of the 26,000-molecular-weight receptor to CFA/I+ bacteria. The CFA/I-specific receptor species also bound to wheat germ agglutinin-agarose. This observation supported the suggestion that the CFA/I receptor identified in this report is a sialoglycoprotein.
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