UNLABELLED The mumps virus (MuV) genome encodes a phosphoprotein (P) that is important for viral RNA synthesis. P forms the viral RNA-dependent RNA polymerase with the large protein (L). P also interacts with the viral nucleoprotein (NP) and self-associates to form a homotetramer. The P protein consists of three domains, the N-terminal domain (P(N)), the oligomerization domain (P(O)), and the C...

In recent years, attention has been focussed on the acceptor function of the serine hydroxyl in various enzymes. Acyl or phosphoryl residues appear to link to it in group transfer, and also in the initial phase of ester or peptide hydrolysis (l-4). This has led to a revival of interest in the classical phosphoproteins, vitellic acid and casein, which carry phosphate on the hydroxyl group of ser...

Attenuated derivative rabies virus Ni-CE replicates in muscle cells less efficiently than does the parental pathogenic strain Nishigahara. To examine the mechanism underlying the less efficient replication of Ni-CE, we compared the activities of Ni-CE and Nishigahara phosphoproteins, viral interferon (IFN) antagonists, to suppress IFN-β promoter activity in muscle cells and we demonstrated a de...

The rates of calcium transport and Ca2+-dependent ATP hydrolysis by rabbit skeletal muscle sarcoplasmic reticulum were stimulated by monovalent cations. The rate of decomposition of phosphoprotein intermediate of the Ca2+-dependent ATPase of sarcoplasmic reticulum was also increased by these ions to an extent that is sufficient to account for the stimulation of calcium transport and Ca2+-depend...

The GTPase Rab13 regulates the assembly of functional epithelial tight junctions (TJs) through a yet unknown mechanism. Here, we show that expression of the GTP-bound form of Rab13 inhibits PKA-dependent phosphorylation and TJ recruitment of the vasodilator-stimulated phosphoprotein, an actin remodelling protein. We demonstrate that Rab13GTP directly binds to PKA and inhibits its activity. Inte...

The low specificity of anti-phosphoprotein antibodies is often a problem in immunoblotting analyses. We introduce a simple pretreatment procedure for cell lysates to give more specific detection of phosphoproteins in immunoblotting. Cellular phosphoproteins were preferentially trapped on Phos-tag agarose phosphate-affinity beads in a homemade spin-centrifuge microtube unit, and nonphosphorylate...

1. An improved method for the preparation of phosphoprotein phosphatase from ox spleen is described. The enzyme was purified 60-fold with a yield of 21 %. 2. The enzyme preparation was free from proteolytic activity and had no action on fl-glycerol phosphate. 3. The enzyme was active on caseins, phenyl phosphate and inorganic pyrophosphate. Hence it cannot be described as a specific phosphoprot...

Protein kinases (Rabinowitz, 1962) catalysing the transfer of the terminal phosphate of ATP to phosvitin, casein and possibly other phosphoproteins have been found in mammalian liver (Burnett & Kennedy, 1954), mammary gland (Sundararajan, Sampath-Kumar & Sarma, 1960), erythrocyte membranes (Judah, Ahmed & McLean, 1962) and brain (Rabinowitz & Lipmann, 1960). The following study of a protein kin...