Tau complexes 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 phospholipase C-gamma (PLC-gamma) signaling pathway. The present study provides support for the physiological relevance of this hypothesis by demonstrating the existence of a tau-PLC-gamma complex in situ in a human neuroblastoma cell line. Both PLC-gamma and PLC-delta, but not PLC-beta, co-purified with microtubule-associated proteins. PLC-gamma, but neither PLC-delta nor PLC-beta, co-immunoprecipitated with tau, and the PLC co-precipitating with tau was enzymatically active. Additionally, both tau and MAP-2 co-precipitated with PLC-gamma. These studies indicate that tau associates, either directly or indirectly, with PLC-gamma in situ, suggesting that tau may be appropriately localized to participate in the regulation of signal transduction through the PLC-gamma pathway in vivo.