Determination of B19-binding protein on surface of T cell line H9. (A) Isolation of B19-binding protein from H9 surface. Surface proteins H9 of cells were biotinylated. Cell lysate from 1 × 10¹¹ biotinylated H9 cells was mixed with rB19ECP-conjugated Sepharose or with BSA-conjugated Sepharose. Precipitated protein was isolated and reacted with streptavidin–horseradish-peroxidase conjugate on PVDF membranes, followed by the chemiluminescence detection. (B) Western blotting of protein from H9 surface with anti-Ku80 antibody. Lanes 1-4 show cell lysate precipitated with indicated protein or protein-conjugated Sepharose. Lane 5 shows the rB19ECP (1 μg) resolved by electrophoresis under denaturing conditions.