Specificity determinants of maize casein kinase-IIB are related to but distinct from those of rat liver casein kinase-2.
The site specificity of maize seedling casein kinase-IIB, a type-2 casein kinase exhibiting an unusually low Mr, has been studied with the aid of model acidic peptide substrates for rat liver casein kinase-2. Like the animal enzyme, casein kinase-IIB also readily phosphorylates peptides SEEEEE, SEAEEE and SEEEAE, but not SEEAEE. Maize seedling casein kinase-IIB, however, is almost inactive toward peptides SAEEEE, SAEEEEE and SAAEEEEE which are good substrates for liver casein kinase-2. This indicates that casein kinase-IIB requires acidic residues not only at position +3, similar to rat liver casein kinase-2, but also at position +1, where the animal enzyme tolerates a neutral residue. This and other differences outlined in this report support the view that protein kinases of the same type from different sources may have significant differences in their substrate specificity.
Dobrowolska
G
G
Dipartimento di Chimica Biologica, Università di Padova, Italy.
Meggio
F
F
Marchiori
F
F
Pinna
L A
LA
D000595:Amino Acid Sequence; D000818:Animals; D047388:Casein Kinases; D007527:Isoenzymes / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D009842:Oligopeptides; D010766:Phosphorylation; D010944:Plants / Q000201:enzymology*; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D013379:Substrate Specificity; D003313:Zea mays / Q000201:enzymology
D007527:Isoenzymes; D009842:Oligopeptides; D011494:Protein Kinases; D047388:Casein Kinases