Functional role of the charge at the T538 residue in the control of protein kinase Ctheta.
We show that protein kinase C (PKC) theta localized at the Golgi complex is partially conjugated to monoubiquitin. Using the inactive T538A and activable T538E mutants of PKCtheta, we demonstrate that the presence of an uncharged residue at the 538 position of the activation loop favors both association with the Golgi and monoubiquitination of the kinase. Moreover, the inactive PKCtheta does not translocate from the Golgi in response to a short-term cell stimulation with a phorbol ester and is subjected to different proteolytic degradation pathways compared to the activable cytosolic kinase. These findings highlight the role of T538 as a critical determinant to address the activable and the inactive PKCtheta molecules to different intracellular compartments and to specific post-transductional modifications. The functional relevance of these observations is supported by the impaired cell division observed in phenotypes expressing high levels of the inactive PKCtheta.
Passalacqua
Mario
M
Department of Experimental Medicine-Biochemistry Section, Centre of Excellence for Biomedical Research, University of Genoa, Viale Benedetto XV, 1-16132 Genoa, Italy. Mario.Passalacqua@unige.it
Pedrazzi
Marco
M
Sparatore
Bianca
B
Patrone
Mauro
M
Pontremoli
Sandro
S
Melloni
Edon
E
D000818:Animals; D001665:Binding Sites; D045744:Cell Line, Tumor; D005822:Genetic Vectors; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004915:Leukemia, Erythroblastic, Acute / Q000201:enzymology / Q000235:genetics; D051379:Mice; D018613:Microscopy, Confocal; D016296:Mutagenesis; D010957:Plasmids; D011493:Protein Kinase C / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000074121:Protein Kinase C-theta; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D013347:Subcellular Fractions / Q000201:enzymology; D025801:Ubiquitin / Q000378:metabolism
D007527:Isoenzymes; D011994:Recombinant Proteins; D025801:Ubiquitin; C489593:Prkcq protein, mouse; D011493:Protein Kinase C; D000074121:Protein Kinase C-theta