Neurogranin binds to phosphatidic acid and associates to cellular membranes

Irene Domínguez-González , Silvia N Vázquez-Cuesta , Alicia Algaba , F Javier Díez-Guerra (1)

1 Depto Biología Molecular, Centro de Biología Molecular Severo Ochoa

Neurogranin (Ng) is a 78 amino acid long protein concentrated at dendritic spines of forebrain neurons that is involved in synaptic plasticity through the regulation of calmodulin (CaM) mediated signalling. Ng features a central IQ motif that mediates binding to CaM and is phosphorylated by protein kinase C (PKC). We have analyzed the subcellular distribution of Ng and found that it associates to cellular membranes in rat brain. In vitro binding assays revealed that Ng selectively binds to phosphatidic acid (PA) and that this interaction is prevented by CaM and PKC phosphorylation. Using the peptide Ng(29-47) and a mutant with an internal deletion (Ng-IQless), we have shown that Ng binding to PA and to cellular membranes is mediated by its IQ motif. Ng expressed in NIH-3T3 cells accumulates at peripheral regions of the plasma membrane and localizes at intracellular vesicles that can be clearly visualized following saponin permeabilization. This distribution was affected by phospholipase D (PLD) and phosphatidylinositol 4-phosphate 5-kinase (PIP5K) overexpression. Based on these results, we propose that Ng binding to PA may be involved in Ng accumulation at dendritic spines and that Ng could modulate PA signalling in the postsynaptic environment.

Mots clés: Life Sciences

Irene Domínguez-González, Silvia N Vázquez-Cuesta, Alicia Algaba, F Javier Díez-Guerra. Neurogranin binds to phosphatidic acid and associates to cellular membranes. Biochemical Journal, 2007, 404 (1), pp.31-43. ⟨10.1042/BJ20061483⟩. ⟨hal-00478674⟩