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doi:10.1093/jmcb/mju051
Journal of Molecular Cell Biology (2014), 6(6), 441
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Editorial
New partners for protein kinases
Protein post-translational modification is a critical
Editor-in-Chief
Jiarui Wu
Institute of Biochemistry and Cell
Biology, Shanghai Institutes for
Biological Sciences, Chinese
Academy of Sciences, Shanghai
200031, China
E-mail: [email protected]
means for the organisms to regulate their activities
(Wu, 2011). Among these modifications, protein
phosphorylation may be the most important one
that involves in the regulation of almost all biological
functions. Protein kinases are the major enzymes that
are responsible for the protein phosphorylation. On
the other hand, protein kinases require other proteins
as the partners to assist or facilitate their kinase activities. In this JMCB issue, four papers deliver new information for us to know more about the partners for
protein kinases.
The review paper by Dr Delia and Buscemi’s groups
systematically reviewed the research progresses of
CHK2 kinase, particularly focusing on its responses
to DNA damage. CHK2 is well known as a nuclear
serine/threonine protein kinase involved in the
spreading of DNA damage signal through a phosphorylation cascade. The authors not only discussed the
classical partners for CHK2 participating in DNA
damage responses, such as ATM and p53, but also
summarized new CHK2 partners including proteins
for cell cycle, circadian clock, and virus infection.
It has been known that flow-induced T-lymphocyte
migration plays an important role in mediating
immune responses. In this issue, Dr Chiu’s laboratory
provided new data for understanding the molecular
mechanisms that caused the directionality and deformation of migratory T-lymphocytes under flow. The
authors showed that protein kinase C (PKC)-d was
enriched in the front of migratory cells and regulated
cell protrusions through Tiam1/Rac1/calmodulin cascades. They further revealed that PKC-b, in coordination
with PKC-d, regulated RhoA/Rho-associated kinase activity to control the T-lymphocyte deformation.
Protein phosphorylation could play both activating
and inhibitory roles in various biological processes.
At the initiation stage of protein translation, phosphorylation of the eukaryotic initiation factor 2a
(eIF2a) inhibits exchange of GDP and ribosome transition along the mRNA. By using a computational approach, Dr Sadler’s group generated a computational
molecular model of eIF2a and the protein kinase R
(PKR). The authors simulated the dynamics of the
interaction between these two molecules and then
predicted a novel kinase– substrate interface, which
was constituted by dynamic residues in both eIF2a
and PKR. They further confirmed these predications
by experimentations.
AMP-activated protein kinase (AMPK) has been
reported to function in many physiological processes,
including promoting saliva secretion in submandibular
glands. In this issue, Dr Xiang and colleagues reported
that claudin-4, a claudin family member as transmembrane protein of tight junction, is required for
AMPK-regulated paracellular permeability in rat submandibular gland cells. The authors showed that
AICAR, an AMPK agonist, induced the phosphorylation
at serine residue of claudin-4 and promoted ERK1/2
phosphorylation. They concluded that claudin-4 and
ERK1/2 were involved in AMPK-modulated tight junction barrier function in submandibular gland.
Reference
Wu, J. (2011). Small changes for works. J. Mol. Cell Biol. 3, 269.
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