Signal Transduction through phosphorylation and dephosphorylation of
proteins in the cell is now a well-recognized mechanism involved in
countless physiological and pathological processes. Consequently, the
enzymes, known as protein kinases, which catalyze the phosphorylation of
proteins, are critical regulators of cellular events. One of these
protein kinases is the protein kinase CK2 (also known as casein kinase
2) that has been implicated in multiple functions including control of
cell growth and proliferation. CK2 is a protein serine/threonine kinase
which is a highly conserved and ubiquitous protein kinase. It is
localized in the cytoplasmic and nuclear compartments, which accords
with its multiple functional activities in the cell. Pertinent to this
is also the recognition that a large number of putative substrates for
this kinase have been identified in various compartments of the cell.
New evidence from several laboratories has further reinforced the
involvement of CK2 in signal transduction related to many cellular
functions, thus underscoring the significance of its functional role in
normal and abnormal cell growth and proliferation.
This volume provides an overview of the state of knowledge concerning
this intriguing protein kinase. It brings together contributions from
leading investigators engaged in research in this field. Key
developments during the past three years pertain to the elaboration of
the crystal structure and definition of novel functions of the kinase,
such as its role as an inhibitor of apoptosis. Additionally, the
shuttling of the kinase to various compartments in response to
physiological and stress stimuli appears to be a key feature of the
functional regulation of its activity in the cell.
