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Casein kinase II phosphorylates Ser 468 in the PEST domain of the Drosophila IκB homologue cactus
Author(s) -
Packman Leonard C,
Kubota Ken,
Parker James,
Gay Nicholas J
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(96)01324-5
Subject(s) - phosphorylation , casein kinase 1 , casein kinase 2 , biology , cactus , proteolysis , transcription factor , cytoplasm , protein kinase a , microbiology and biotechnology , casein kinase 2, alpha 1 , kinase , phosphoprotein , protein kinase domain , biochemistry , mitogen activated protein kinase kinase , botany , gene , enzyme , mutant
Cactus protein is a Drosophila homologue of the mammalian IκB family of cytoplasmic anchor proteins. In unstimulated cells they function to retain rel/NFκB transcription factors in the cytoplasm but are rapidly degraded in response to signalling. The destruction of cactus or IκBα allows the rel/NFκB transcription factor to relocalise to the nucleus. Cactus is a phosphoprotein and has in its C‐terminus a PEST protein stability domain. In this paper we show that, like mammalian IκBα, the PEST domain of cactus is phosphorylated by casein kinase II. We have localised the site of modification to a single residue, Ser 468 , and find no evidence for additional phosphorylation sites. The conservation of these sites in mammalian and invertebrate cytoplasmic anchor proteins suggests that phosphorylation by casein kinase II may play a critical functional role, plausibly in the regulation of constitutive or inducible proteolysis.