Critical role of novel Thr-219 autophosphorylation for the cellular function of PKCtheta in T lymphocytes.
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Thuille N, Heit I, Fresser F, Krumbock N, Bauer B, Leuthaeusser S, Dammeier S, Graham C, Copeland TD, Shaw S, Baier G
Critical role of novel Thr-219 autophosphorylation for the cellular function of PKCtheta in T lymphocytes.
EMBO J. 2005 Nov 16;24(22):3869-80. Epub 2005 Oct 27.
- PubMed ID
- 16252004 [ View in PubMed]
- Abstract
Phosphopeptide mapping identified a major autophosphorylation site, phospho (p)Thr-219, between the tandem C1 domains of the regulatory fragment in protein kinase C (PKC)theta. Confirmation of this identification was derived using (p)Thr-219 antisera that reacted with endogenous PKCtheta in primary CD3+ T cells after stimulation with phorbol ester, anti-CD3 or vanadate. The T219A mutation abrogated the capacity of PKCtheta to mediate NF-kappaB, NF-AT and interleukin-2 promoter transactivation, and reduced PKCtheta's ability in Jurkat T cells to phosphorylate endogenous cellular substrates. In particular, the T219A mutation impaired crosstalk of PKCtheta with Akt/PKBalpha in NF-kappaB activation. Yet, this novel (p)Thr-219 site did not affect catalytic activity or second-messenger lipid-binding activity in vitro. Instead, the T219A mutation prevented proper recruitment of PKCtheta in activated T cells. The PKCthetaT219A mutant defects were largely rescued by addition of a myristoylation signal to force its proper membrane localization. We conclude that autophosphorylation of PKCtheta at Thr-219 plays an important role in the correct targeting and cellular function of PKCtheta upon antigen receptor ligation.