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KMID : 0613820060160040612
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Journal of Life Science
2006 Volume.16 No. 4 p.612 ~ p.617
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Phospholipase C-γ1 Activation by Direct Interaction with β-Tubulin Isotypes
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Lee In-Bum
Kim Sung-Kuk
Choi Jang-Hyun
Suh Pan-Ghil
Jang Jong-Soo
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Abstract
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Phosphoinositide-specific phospholipase C-γ1 (PLC-γ1) has pivotal roles in cellular signaling by producing second messengers, inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DG). Tubulin is a main component of microtubules and mitotic spindle fibers, which are composed of α- and β-tubulin heterodimers in all eukaryotic cells. In humans, six β-tubulin isotypes have been identified which display a distinct pattern of tissue expression. Previously we found that PLC-γ1 and one of four β-tubulin isotypes including β1, β2, β3 and β6, colocalized in COS-7 cells and cotranslocated to the plasma membrane to activate PLC-γ1 upon agonist stimulation. In the present study, we demonstrate that the remaining two, tubulin β4 and β5, also showed a potential to activate PLC-γ1. The phosphatidylinositol 4,5-bisphosphate (PIP₂) hydrolyzing activity of PLC-γ1 was substantially increased in the presence of purified β4 and β5 tubulin in vitro, whereas the activity was not promoted by bovine serum albumin, suggesting that tubulin β4 and β5 also activate PLC-γ1. Taken together, our results suggest that all the β-tubulin isotype activates PLC-γ1 activity to regulate cellular signaling.
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KEYWORD
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Phospholipase C-γ1, β-tubulin isotype, immunocytochemistry, GST pull down assay
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