Abstract
The subcellular distributions of endogenous ADP-ribosylation products in hearts from 1-day-old neonatal and adult rats were investigated. In adult rat heart a 52 kDa mono-ADP-ribosylation product was identified in the plasma membrane fraction. In contrast, in neonatal rat heart a 130 kDa poly-ADP-ribosylation product was present in the nuclear fraction. The monomeric and polymeric nature of the two ADP-ribosylation products was determined by their sensitivity to thymidine and by analysis of their snake venom phosphodiesterase products. NADP+ enhanced both the mono- and polymeric reactions. The ADP-ribose-protein linkage of the adult 52 kDa product was stable to 1 h of treatment with hydroxylamine (0.5 M) and mercury ions, but was sensitive to alkali and a 12 h treatment with hydroxylamine (1 M). This is suggestive of an arginine linkage. The 130 kDa poly-ADP-ribosylation product from the neonatal rat heart was alkalilabile but stable to both hydroxylamine and HgCl2. This implies the presence of an unusual linkage in the 130 kDa product. The presence of these different ADP-ribosylation products in adult and neonatal rat hearts suggests the possible importance of these proteins and their ADP-ribosylation during cardiac development.