Regulation of brain G-protein Go by Alzheimer's disease gene presenilin-1

To investigate a possible association between G-proteins and presenilin-1 (PS-1), a series of glutathione S-transferase-fusion proteins containing portions of PS-1 were prepared and used in vitro in binding experiments with tissue and recombinant G-proteins. The results demonstrate that the 39 C-terminal amino acids of PS-1 selectively bind the brain G-protein, G(o). Addition of guanosine 5'-3-O-(thio)triphosphate promoted G(o) dissociation from PS-1, indicating that this domain mimics the function of G-protein-coupling domains found in receptors. The 39-amino acid synthetic polypeptide activated G(o) in a magnesium ion-dependent manner, Physical interaction of full-length PS-1 and G(o) was also demonstrated. Following transfection of G(o alpha) and N-terminally FLAG-tagged PS-1 in COS-7 cells, G(o) was immunoprecipitated by FLAG antibodies. In addition, endogenous PS-1 and G(o alpha) were colocalized immunocytochemically in human glioma cell lines. The results indicate that PS-1 regulates G(o) activities in living cells.