J A Ptasienski

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Recent studies have identified agonist-dependent phosphorylation as a critical event in the rapid uncoupling of the m2 muscarinic cholinergic receptors (mAChR) from G-proteins and sequestration of the receptors away from the cell surface. However, mutant m2 mAChRs were identified that were phosphorylated but unable to desensitize in adenylyl cyclase assays,(More)
Chick heart membranes were labelled with [3H]PN 200-110, a 1,4-dihydropyridine calcium channel antagonist. The [3H]PN 200-110 receptors were solubilized with digitonin and purified 600-fold using several chromatographic systems and sucrose density gradient centrifugation. Analyses by gel electrophoresis revealed that the final product was enriched in two(More)
Arrestins play an important role in quenching signal transduction initiated by G protein-coupled receptors. To explore the specificity of arrestin-receptor interaction, we have characterized the ability of various wild-type arrestins to bind to rhodopsin, the beta 2-adrenergic receptor (beta 2AR), and the m2 muscarinic cholinergic receptor (m2 mAChR).(More)
Dihydropyridine-sensitive Ca2+ channels exist in many different types of cells and are believed to be regulated by various protein phosphorylation and dephosphorylation reactions. The present study concerns the phosphorylation of a putative component of dihydropyridine-sensitive Ca2+ channels by the calcium and phospholipid-dependent protein kinase, protein(More)
G protein-coupled receptor-mediated signaling is attenuated by a process referred to as desensitization, wherein agonist-dependent phosphorylation of receptors by G protein-coupled receptor kinases (GRKs) is proposed to be a key initial event. However, mechanisms that activate GRKs are not fully understood. In one scenario, beta gamma-subunits of G proteins(More)
Partially purified fractions of dihydropyridine and phenylalkylamine receptors associated with voltage-dependent calcium channels in rabbit skeletal muscle were found to contain two glycopeptides of similar molecular weight. A peptide of approximately 165 kDa was photoaffinity labelled with an arylazido-phenylalkylamine Ca channel inhibitor and also was(More)
The studies reported here address the molecular events underlying the interactions of arrestins with the M(2) muscarinic acetylcholine receptor (mAChR). In particular, we focused on the role of receptor phosphorylation in this process. Agonist-dependent phosphorylation of the M(2) mAChR can occur at clusters of serines and threonines at positions 286-290(More)
We have determined whether the process of agonist-mediated phosphorylation of the muscarinic receptor correlates with the process of muscarinic receptor desensitization in chick cardiac tissue. Exposure of ventricular slices to the agonist carbachol under conditions previously shown to lead to large increases in muscarinic receptor phosphorylation (Kwatra,(More)