Fig. 3.

Co-purification of SEAP and a co-migrating sialoglycoprotein. Phosphoaffinity purifications were performed with the cell-free medium from AcSEAP-infected SfSWT-1 cells, AcSEAP-infected Tn-4h cells, or mock-infected Tn-4h cells or with fetal bovine serum alone, as the starting materials as described in Materials and methods. Equal aliquots of the purified column eluants were then treated with buffer alone (−) or neuraminidase (+) and analyzed by (A) SDS-PAGE and immunoblotting with a SEAP-specific antibody or (B) SDS-PAGE and SNA lectin blotting, as described in Materials and methods. The arrows on the left-hand side of the figure mark the position of the 66.4-kDa standard.