Neurogranin, a B-50/GAP-43-immunoreactive C-kinase substrate (BICKS), is ADP-ribosylated

Neurogranin is a neurone-specific, B-50-immunoreactive C-kinase substrate that has limited homology to, but considerable biochemical similarity to B-50/GAP43. The most significant differences between these two proteins are their cellular localisation and molecular mass (Neurogranin, 7.5 kDA cytosolic; and B-50, 25 kDa membranal). An understanding of the similarities and differences between Neurogranin and B-50 may facilitate the elucidation of their hitherto elusive functions in the nervous system. The results of the present study demonstrate that, in common with B-50, Neurogranin is a substrate for ADP-ribosyltransferase. This finding is discussed with regard to the concept of molecular flexibility of B-50-like proteins as the basis of their putatively diverse roles in the nervous system.