Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.
Phosphatidylinositol-3 kinase-related kinases (PIKKs) is a class of six unique serine/threonine kinases that are characterized as high molecular mass colossal proteins present in multicellular organisms. They predominantly regulate the innumerable eukaryotic cellular processes, for instance, cell-signaling cascades related to DNA damage and repair, cell growth and proliferation, cell cycle arrest, genome surveillance, gene expression and many other important yet diverse functions. A characteristic PIKK member comprises of an N-terminal HEAT domain, followed by FAT domain, a highly conserved kinase catalytic domain, and a C-terminal FATC domain. In this comprehensive review, we reassess and discuss various established functions of all the six PIKK members with each function corroborated by their structural topology. In addition to the domain architecture of these atypical kinases, their specific inhibitors have been briefly deliberated. This review gives us the impression of the emergent importance of PIKKs, which, despite of their complexity, are the hub of research with respect to the inhibitor development.