Crystal structure of human protein kinase CK2: insights into basic properties of the CK2 holoenzyme

Abstract

The crystal structure of a fully active form of human protein kinase CK2 (casein kinase 2) consisting of two C‐terminally truncated catalytic and two regulatory subunits has been determined at 3.1 Å resolution (Protein Data Bank code: 1JWH). In the CK2 complex the regulatory subunits form a stable dimer linking the two catalytic subunits, which make no direct contact with one another. Each catalytic subunit interacts with both regulatory chains, predominantly via an extended C‐terminal tail of the regulatory subunit. The CK2 structure is consistent with its constitutive activity and with a flexible role of the regulatory subunit as a docking partner for various protein kinases. Furthermore it shows an inter‐domain mobility in the catalytic subunit known to be functionally important in protein kinases and detected here for the first time directly within one crystal structure.