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Pseudokinase domain of Tribbles Homolog 3 The pseudokinase domain shows similarity to protein kinases but lacks crucial residues for catalytic activity. TRB3 binds and regulates ATF4, p65/RelA, and PKB (or Akt). It negatively regulates ATF4-mediated gene expression including that of CHOP (C/EBP homologous protein) and HO-1, which are both involved in modulating apoptosis. It also inhibits insulin-mediated phosphorylation of PKB and is a possible determinant of insulin resistance and related disorders. In osteoarthritic chondrocytes where it inhibits insulin-like growth factor 1-mediated cell survival, TRB3 is overexpressed, resulting in increased cell death. TRB3 is one of three Tribbles Homolog (TRB) proteins present in vertebrates that are encoded by three separate genes. TRB proteins interact with many proteins involved in signalling pathways. They play scaffold-like regulatory functions and affect many cellular processes such as mitosis, apoptosis, and gene expression. The TRB3 subfamily is part of a larger superfamily that includes the catalytic domains of serine/threonine kinases, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",