title: Receptors for fibrinogen and aggregated beta 2-microglobulin detected in strains of group B streptococci.
abstract: Binding of radiolabeled human fibrinogen and aggregated beta-microglobulin was measured in 60 strains of beta-hemolytic group B streptococci. Positive fibrinogen binding was detected in seven of the strains. Six of the group B strains showed an uptake of aggregated beta 2-microglobulin. Four individual strains carried both receptors, indicating a positive correlation between their occurrence. Inhibition studies showed that fibrinogen competed sterically with beta 2-microglobulin binding. Receptors for both proteins were trypsin sensitive. The presence of receptors did not correlate with the serological type of the 49 group B strains tested. However, all seven type II strains were negative. No uptake of fibrinogen was noted in any of 40 group D strains tested. Binding structures for fibrinogen and aggregated beta 2-microglobulin detected in group B streptococci were similar to receptors for the same proteins in group A, C, and G streptococci in terms of mutual correlation and steric interference of binding. The occasional occurrence of these receptors also in group B strains might reflect a common origin of some types of surface proteins in gram-positive cocci.
mesh_terms: D001609:Beta-Globulins / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism*; D010980:Platelet Membrane Glycoproteins; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011971:Receptors, Immunologic / Q000378:metabolism*; D013292:Streptococcus agalactiae / Q000378:metabolism*; D014357:Trypsin / Q000378:metabolism; D001613:beta 2-Microglobulin / Q000378:metabolism*
chemical_list: D001609:Beta-Globulins; D010980:Platelet Membrane Glycoproteins; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; C027292:beta 2 microglobulin receptor; D001613:beta 2-Microglobulin; D005340:Fibrinogen; D014357:Trypsin