FIG. 1.

(A) Strategy used to delete or replace the C-terminal (C-term) lysine residues (K428, K434, and K435) by site-directed mutagenesis and the resultant His-tagged recombinant SEN proteins. Primer 1 (sen-F-NdeI) is a common forward primer and contains an NdeI site. Primers 2 to 7 are reverse primers each with a restriction site for BamHI used to construct wild-type SEN (SEN-wt) and mutated SEN proteins with their C-terminal and penultimate lysine residues either deleted or replaced with leucines (see Table 1). N-term, N terminal. (B) Western blot analysis showing the antibody reactivities of different purified recombinant (Rec) SEN proteins with affinity-purified rabbit polyclonal anti-SEN antibodies (Ab) and their plasminogen (Plg)-binding activities with ¹²⁵I-labeled Glu-plasminogen and ¹²⁵I-labeled Lys-plasminogen in the presence or absence of 0.1 M EACA.