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Role of the kinase activation loop on protein kinase C θ activity and intracellular localisation
Author(s) -
Sparatore Bianca,
Passalacqua Mario,
Pedrazzi Marco,
Ledda Sabina,
Patrone Mauro,
Gaggero Deborah,
Pontremoli Sandro,
Melloni Edon
Publication year - 2003
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(03)01073-1
Subject(s) - intracellular , protein kinase c , kinase , microbiology and biotechnology , protein kinase a , phosphorylation , biology , biochemistry , golgi apparatus , chemistry , cell
Multiple protein kinase C (PKC) θ species, identified in an erythroleukaemia cell line, have been characterised in terms of their molecular properties and intracellular distribution. PKCθs localised in the detergent‐soluble cell fraction have an M r of 76 kDa (θ‐76) and contain Thr 538 or pThr 538 in the kinase activation loop. In contrast, PKCθs localised in the Golgi complex have an M r of 85 kDa (θ‐85) and, although unphosphorylated at Thr 538 , are catalytically active. Strikingly, only θ‐76 species which are unphosphorylated at Thr 538 can undergo autocatalytic conversion to θ‐85. Moreover, a Thr 538 →Ala PKCθ mutant is constitutively localised in the Golgi complex, confirming that changes in the phosphorylation state of this residue play a pivotal role in the overall control of catalytic properties and localisation of this kinase.