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KMID : 0614020040190010070
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Journal of Pharmaceutical Sciences (C.N.U.)
2004 Volume.19 No. 1 p.70 ~ p.77
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Differential Role of Acetylspermine in Regulating Gβγ-mediated Effector Activation
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Myung Chang-Seon
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Abstract
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Heterotrimeric G protein βγ subunit (Gβγ) is known to be an important transducer in the G protein coupled receptors-induced signaling system by interacting with membrane-associated proteins or effectors. While there are several ways to regulate the activity of G protein a subunit (Gα), the regulatory mechanisms for the activity of Gβγ is unclear. This study was designed to examine whether acetylated metabolite of endogenous spermine, acetylspermine, can regulate the effector activity by Gβγ. Gβ₁γ₂ was over-expressed in baculovirus/Sf9 insect cell system, purified, and effect of acetylspermine on the ability of Gβ₁γ₂ to stimulate both phospholipase C-β isoform (PLC-β) and type Ⅱ adenylyl cyclase (AC Ⅱ) was measured. Gβ₁γ₂ activated PLC-β and AC 11 about 13 and 15 folds, respectively in a dose-dependent manner. The preincubation for acetylspermine to interact with either 8~ or PLC-8 enzyme caused a complete blockade of the activation of PLC-β by Gβ₁γ₂. In contrast, similar experiments showed that acetyspemine potentiated the activity of AC Ⅱ by Gβ₁γ₂. Therefore, the results demonstrate that the activities of Gβγ on effectors are differently regulated by acetylspermine, and acetylpolyamines might be endogenous regulators of Gβγ signaling.
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KEYWORD
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acetylpolyamines, heterotrimeric G protein, βγ subunits, phospholipase C-β, adenyl cyclase
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