TAU-COMPLEX WITH PHOSPHOLIPASE C-GAMMA IN-SITU

BASED on the results of recent in vitro studies, tau has been proposed to be involved in regulating signal transduction through the phosphol ipase C-gamma (PLC-gamma) signaling pathway. The present study provide s support for the physiological relevance of this hypothesis by demons trating the existence of a tau-PLC-gamma complex in situ in a human ne uroblastoma cell line. Both PLC-gamma and PLC-delta, but not PLC-beta, co-purified with microtubule-associated proteins. PLC-gamma, but neit her PLC-delta nor PLC-beta, co-immunoprecipitated with tau, and the PL C co-precipitating with tau was enzymatically active. Additionally, bo th tau and MAP-2 co-precipitated with PLC-gamma. These studies indicat e that tau associates, either directly or indirectly, with PLC-gamma i n situ, suggesting that tau may be appropriately localized to particip ate in the regulation of signal transduction through the PLC-gamma pat hway in vivo.