When the crude phosphoprotein phosphatase fraction of rat liver cytosol was treated with 80% aqueous ethanol at room temperature, the activity with phosphorylase alpha as substrate was increased by 110%, but those with glycogen synthase D and phosphohistone were decreased by 53 and 34%, respectively. Chromatography of the ethanol-treated fraction on DE-52 revealed that while phosphoprotein phos...

Proteins subject to proteolysis or phosphorylation during apoptosis are commonly precipitated by autoantibodies found in the serum of patients with systemic lupus erythematosus (SLE). We screened a panel of murine monoclonal and human monospecific sera reactive with known autoantigens for their ability to selectively precipitate phosphoproteins from apoptotic Jurkat T cell lysates. Sera known t...

The present study documents the existence in mammalian brain of a phosphoprotein which may play a biological role in dopaminoceptive neurons. This protein has been designated DARPP-32 (dopamine- and adenosine 3':5'-monophosphate-regulated phosphoprotein-32,000). The regional distribution of DARPP-32 in the rat brain follows the general pattern of dopaminergic innervation. DARPP-32 is present in...

MOTIVATION Signaling networks mediate responses to different stimuli using a multitude of feed-forward, feedback and cross-talk mechanisms, and malfunctions in these mechanisms have an important role in various diseases. To understand a disease and to help discover novel therapeutic approaches, we have to reveal the molecular mechanisms underlying signal transduction and use that information to...

The present study reports the existence of Purkinje cell-specific phosphoprotein, Mr 260,000 (PCPP-260), a neuronal membrane phosphoprotein, in cerebellar Purkinje cells. PCPP-260, which on sodium dodecyl sulfate-polyacrylamide gel electrophoresis has an apparent molecular mass of 260,000 Da, has been found to be phosphorylated in particulate preparations by endogenous or added exogenous cyclic...

Mutations in the ligand-binding domain of the epidermal growth factor receptor have been identified in several types of human cancers, including malignant gliomas. These mutations render signaling by this receptor to be constitutively ligand-independent. In fibroblasts transformed with ligand-independent epidermal growth factor receptor mutants, there is a correlation between the formation of a...

One of the major structural differences between rabies virus and vesicular stomatitis virus (VSV) is that the nucleoprotein (N) is the major phosphoprotein and the nominal phosphoprotein (P) is less phosphorylated in rabies virus, whereas P is the major phosphoprotein and N is not phosphorylated in VSV. We investigated the function of phosphorylation of rabies virus N after dephosphorylation of...

Type-2 calcium-dependent potassium (KCa) channels from mammalian brain, reconstituted into planar phospholipid bilayers, are modulated by ATP or ATP analogs via an endogenous protein kinase activity intimately associated with the channel (Chung et al., 1991). We show here that the endogenous protein kinase activity is protein kinase C (PKC)-like because (1) modulation by ATP can be mimicked by ...

Protein phosphorylation plays a key role in regulating nearly all intracellular biological events. However, poorly developed phospho-specific antibodies and low phosphoprotein abundance make it difficult to study phosphoproteins. Cellular protein phosphorylation data have been obtained using phosphoproteomic approaches, but the detection of low-abundance or fast-cycling phosphorylation sites re...