Isoproterenol‐stimulated labelling of particulate proteins by using [adenylate‐32P]NAD+ independent on a cAMP‐dependent protein kinase in parotid acinar ells

[摘要]

When saponin-permeabilized rat parotid acinar cells were incubated with [adenylate-³²P]NAD⁺, labelling of proteins (33₊ 27 and 23 kDa) in particulate fractions of the cells was stimulated by isoproterenol. The effect of isoproterenol was completely blocked by a β-antagonist. Both forskolin or CAMP mimicked the effect of isoproterenol on the labelling. However, an inhibitor of cAMPdPK failed to induce complete inhibition of the effects of isoproterenol, forskolin and cAMP. When the labelled proteins were treated with snake venom phosphodiesterase, neither [³²P]5′-AMP nor [³²P]phosphoribosyladenosine was released. These results suggest that covalent modification of proteins with NAD⁺, which is distinct from ADP-ribosylation and cAMPdPK-dependent phosphorylation, is coupled to β-receptor-cAMP signalling system in rat parotid acinar cells.

[学科分类] 生物化学/生物物理

[关键词] Isoproterenol;NAD+;Cyclic AMP;Phosphorylation;ADP-ribosylation;Parotid;cAMP;cyclic AMP;cAMPdPK;cyclic AMP-dependent protein kinase;IBMX;3-isobutyl-1-methylxanthine;H-8;N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide;HEPES;4-(2-hydroxyethyl)-1-piperazincethanesulfonic acid