THE AMYLOID PRECURSOR PROTEIN-FRAGMENT HIS-657-LYS-676 INHIBITS NORADRENALINE-INDUCED AND ENKEPHALINE-INDUCED SUPPRESSION OF VOLTAGE-SENSITIVE CALCIUM CURRENTS IN NG108-15 HYBRID-CELLS

We have investigated the effects of the C-terminal amyloid precursor p rotein fragment His 657-Lys 676 upon calcium currents in NG108-15 neur oblastoma x glioma hybrid cells. The amyloid precursor protein fragmen t His 657-Lys 676 (1-10 mu M) did not affect calcium currents pel se, but clearly blocked the calcium current suppression mediated by both a drenergic alpha(2B)- and opioid delta receptors in a concentration-dep endent manner. The reverse amyloid precursor protein fragment Lys 676- His 657 and the shorter amyloid precursor protein fragment Gly 659-Lys 676 did not affect calcium current suppression by adrenergic alpha(2B )- and opioid delta receptors. The similar interaction of C-terminal a myloid precursor protein with adrenergic alpha(2B)- and opioid delta r eceptors suggest that the effect occurs downstream of the receptor, po ssibly via the GTP binding protein G(o).