Protein kinase C theta type

Protein kinase C theta type (PRKCQ) is a calcium-independent serine/threonine kinase that mediates T-cell receptor signaling, driving T-cell activation, proliferation, and survival through phosphorylation of key transcription factors including NF-κB, JUN, and NFAT family members (UniProt: Q04759). The enzyme also regulates platelet activation and may modulate insulin signaling via IRS1 phosphorylation.

PRKCQ is primarily expressed in immune cells, particularly T-lymphocytes and platelets, where it orchestrates signaling cascades downstream of TCR/CD28 costimulation and platelet receptors. Beyond immune function, the protein participates in diverse cellular processes including actin cytoskeleton regulation and intracellular trafficking through phosphorylation of effector proteins such as LRRK1 and MSN.

In Alzheimer's disease, PRKCQ exhibits reduced abundance in post-mortem AD brain tissue compared to age-matched controls (Chaparral AD proteomics). The protein was significantly downregulated with a mean log2 fold-change of −0.54 across analyzed subcellular fractions in TMT-labeled proteomics, suggesting potential dysregulation of immune signaling pathways or T-cell dysfunction in AD pathogenesis.