Identification and characterization of novel components of a Ca2+/calmodulin-dependent protein kinase cascade in HeLa cells.
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Ishikawa Y, Tokumitsu H, Inuzuka H, Murata-Hori M, Hosoya H, Kobayashi R
Identification and characterization of novel components of a Ca2+/calmodulin-dependent protein kinase cascade in HeLa cells.
FEBS Lett. 2003 Aug 28;550(1-3):57-63.
- PubMed ID
- 12935886 [ View in PubMed]
- Abstract
In this report, we cloned a novel calmodulin-kinase (CaM-KIdelta) from HeLa cells and characterized its activation mechanism. CaM-KIdelta exhibits Ca(2+)/CaM-dependent activity that is enhanced (approximately 30-fold) in vitro by phosphorylation of its Thr180 by CaM-K kinase (CaM-KK)alpha, consistent with detection of CaM-KIdelta-activating activity in HeLa cells. We also identified a novel CaM-KKbeta isoform (CaM-KKbeta-3) in HeLa cells whose activity was highly Ca(2+)/CaM-independent. Transiently expressed CaM-KIdelta exhibited enhanced protein kinase activity in HeLa cells without ionomycin stimulation. This sustained activation of CaM-KIdelta was completely abolished by Thr180Ala mutation and inhibited by CaM-KK inhibitor, STO-609, indicating a functional CaM-KK/CaM-KIdelta cascade in HeLa cells.