Fig. 1. Proteolytic processing of Ea by active Snk. An immunoblot, using anti-Ea specific antiserum, of conditioned cell culture medium from co-expression of Ea proenzyme (50 kDa) and increasing amounts of SnkΔn, a constitutively active form of Snk. Lanes (from left to right) correspond to: Ea partially digested in vitro with trypsin; Ea alone; and Ea with 1/100, 1/50, 1/20, one-fifth and an equal volume of SnkΔn (v/v ratio of high titer stocks). The 35 kDa polypeptide corresponds to the size previously reported for the active Ea catalytic chain.