Catalytic domain of the Serine/Threonine Kinase, Novel Protein Kinase C theta
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. PKC-theta is selectively expressed in T-cells and plays an important and non-redundant role in several aspects of T-cell biology. Although T-cells also express other PKC isoforms, PKC-theta is unique in that upon antigen stimulation, it is translocated to the plasma membrane at the immunological synapse, where it mediates signals essential for T-cell activation. It is essential for TCR-induced proliferation, cytokine production, T-cell survival, and the differentiation and effector function of T-helper (Th) cells, particularly Th2 and Th17. PKC-theta is being developed as a therapeutic target for Th2-mediated allergic inflammation and Th17-mediated autoimmune diseases. PKCs are classified into three groups (classical, atypical, and novel) depending on their mode of activation and the structural characteristics of their regulatory domain. nPKCs are calcium-independent, but require DAG (1,2-diacylglycerol) and phosphatidylserine (PS) for activity. The nPKC subfamily is part of a larger superfamily that includes the catalytic domains of other STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.
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