“…We have previously used confocal imaging to detect the translocation of eGFP-PH PLC␦ as an IP 3 biosensor (18,22) to investigate M 1 mACh receptor regulation of PLC activity in hippocampal neurons. Using this approach, we showed that GRK2 inhibits M 1 mACh receptor signaling in hippocampal neurons via a phosphorylation-independent mechanism (18) 1 The abbreviations used are: mACh, muscarinic acetylcholine; PLC, phosphoinositide-specific phospholipase C; GPCR, G protein-coupled receptor; PKC, protein kinase C; CHO, Chinese hamster ovary; MCh, methacholine; IP 3 , inositol 1,4,5-trisphosphate; GRK, G protein-coupled receptor kinase; RH, RGS homology; eGFP, enhanced green fluorescent protein; HA, hemagglutinin; PDBu, phorbol 12,13-dibutyrate; ERK, extracellular signal-regulated kinase; MEK, mitogen-activated protein kinase/ERK kinase; JNK, c-Jun N-terminal kinase; AM, acetoxymethyl ester; BAPTA, 1,2-bis(O-aminophenoxy)ethane-N,N,NЈ,NЈ-tetraacetic acid; BAPTA-AM, 1,2-bis(O-aminophenoxy)ethane-N,N,NЈ,NЈ-tetraacetic acid tetra(acetoxymethyl) ester.…”