ISSN:
1573-4919
Keywords:
protein kinase CK2
;
casein kinase 2
;
substrate recognition
;
heparin
;
phosphoaceptor peptides
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Abstract Protein kinase CK2 is characterized by a number of features, including substrate specificity, inhibition by polyanionic compounds and intrasteric down-regulation by its β-subunit, which denote a special aptitude to interact with negatively charged ligands. This situation may reflect the presence in CK2 catalytic subunits of several basic residues that are not conserved in the majority of other protein kinases. Some of these residues, notably K49 in the ‘Gly rich loop’, K74, K75, K76, K77, K79, R80, K83 in the ‘Lys rich segment’ and R191, R195, K198 in the ‘p+1 loop’, have been shown by mutational studies to be implicated to various extents and with distinct roles in substrate recognition, inhibition by heparin and by pseudosubstrate and instrasteric regulation. Molecular modelization based on crystallographic data provide a rationale for the biochemical observations, showing that several of these basic residues are clustered around the active site where they make contact with individual acidic residues of the peptide substrate. They can also mediate the effect of polyanionic inhibitors (e.g. heparin) and of regulatory elements present in the b-subunit, in the N terminal segment of the catalytic subunit and possibly in other proteins interacting with CK2. Our data also disclose a unique mode of binding of the phosphoacceptor substrate which bridges across the catalytic cleft making contacts with both the lower and upper lobes of CK2.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1006857016712
Permalink
