Purification and characterization of two forms of XXXX -dependent protein kinase from @entity291 aorta.

@entity6708 @entity268 @entity10644 @entity3208 @entity8262 @entity2975 @entity8851 @entity3367 @entity1329 @entity291
@entity8262 -dependent protein kinase in extracts of @entity291 aortic tissue eluted from @entity8851 -cellulose ion-exchange resins as two distinct peaks of activity. This elution pattern was preserved when the peaks were combined, precipitated with @entity1329 , dialyzed, and rechromatographed. Proteolysis did not appear to account for the two forms of kinase because (i) aging of the extract did not cause interconversion of the two forms, and (ii) both forms retained @entity6708 sensitivity unlike the proteolytically formed monomer. In addition, treatment with saturating concentrations of @entity6708 (10 microM) did not cause interconversion of the two forms. The first peak of @entity6708 -dependent protein kinase eluting from DEAE-cellulose (form 1) had a slightly greater mobility on gradient @entity3208 - @entity2975 gels than the second peak (form 2). On native, nondenaturing gradient @entity2975 gels, however, form 2 displayed the greater electrophoretic mobility. Furthermore, form 1, when bound to @entity268 - @entity3367 , appeared to exchange more rapidly with @entity6708 than form 2 when subjected to affinity chromatography. Peptide maps generated from the two forms by protease treatment were very similar, although trypsin produced a unique peptide in form 1 and @entity10644 protease gave rise to unique peptides in forms 1 and 2. Phosphorylation did not appear to account for the physical differences because both enzymes could be phosphorylated to similar extents and dephosphorylation using alkaline phosphatase did not result in the conversion of one form to the other. These results suggest that either differences in primary structure or post-translational modification, other than phosphorylation, are responsible for the presence of two forms of @entity6708 -dependent protein kinase in aortic tissue.
