PKC can potentiate AHNAK-dependent activation of PLC-γ isozyme

다국어 초록 (Multilingual Abstract)

We have recently shown that phospholipase C-γ(PLC-γ) is activated by AHNAK protein in the presence of arachidonic acid. Several reports suggest that AHNAK protein is phosphorylated by PKC and then localized to plasma membrane. To verify the effect of phosphorylation of AHNAK protein by PKC on PLC-γactivity, PIP2-hydrolyzing activity of PLC-γ was determined. Phosphorylation of AHNAK by PKC potentiates PLC-γ activity in the presence of arachidonic acid. Stimulation of NIH3T3 2.2 cells overexpressing AHNAK with PMA induced total inositol phosphate(IP_(γ)) generation compared to control NIH3T3 2.2 cells exposed to PMA. The results suggest that PKC can activate PLC-γ indirectly through phosphorylation of AHNAK protein. AHNAK protein is unusual. large protein(700kDa) and comprises about 30 repeated motif each 128 amino acids in length. To identify the association protein with a repeated motif of AHNAK, we employed yeast two hybridization using one repeated motif(R1) as bait. The results of the yeast two hybridization are shown that one repeated motif of AHNAK interacted strongly with the receptor for activated C-kinase(RACK). It is likely that AHNAK protein acts as a scafolding protein networking with PLC-γ, RACK and PKC.