Ultrastructural localization of apamin binding sites in guinea pig intestinal smooth muscle

Binding sites of the neurotoxin apamin were located by immunocytochemical analysis using apamin antibodies. It was found that these bindings sites were located on the plasma membrane of smooth muscle cells in the longitudinal muscle of the cecum and at the nerve terminals in the guinea pig.A. V. Palladin Institute of Biochemistry, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 17, No. 6, pp. 824–827, November–December, 1985.     

Intragenic duplication and divergence in the spectrin superfamily of proteins

Many structural, signaling, and adhesion molecules contain tandemly repeated amino acid motifs. The alpha-actinin/spectrin/dystrophin superfamily of F-actin-crosslinking proteins contains an array of triple alpha-helical motifs (spectrin repeats). We present here the complete sequence of the novel beta-spectrin isoform beta(Heavy)- spectrin (beta H). The sequence of beta H supports the origin of alpha- and beta-spectrins from a common ancestor, and we present a novel model for the origin of the spectrins from a homodimeric actin-crosslinking precursor. The pattern of similarity between the spectrin repeat units indicates that they have evolved by a series of nested, nonuniform duplications. Furthermore, the spectrins and dystrophins clearly have common ancestry, yet the repeat unit is of a different length in each family. Together, these observations suggest a dynamic period of increase in repeat number accompanied by homogenization within each array by concerted evolution. However, today, there is greater similarity of homologous repeats between species than there is across repeats within species, suggesting that concerted evolution ceased some time before the arthropod/vertebrate split. We propose a two-phase model for the evolution of the spectrin repeat arrays in which an initial phase of concerted evolution is subsequently retarded as each new protein becomes constrained to a specific length and the repeats diverge at the DNA level. This evolutionary model has general applicability to the origins of the many other proteins that have tandemly repeated motifs.      

Comparisons of the molecular evolutionary process at rbcL and ndhF in the grass family (Poaceae)

We examine rate heterogeneity among evolutionary lineages of the grass family at two plasmid loci, ndhF and rbcL, and we introduce a method to determine whether patterns of rate heterogeneity are correlated between loci. We show both that rates of synonymous evolution are heterogeneous among grass lineages and that are heterogeneity is correlated between loci at synonymous sites. At nonsynonymous sites, the pattern of rate heterogeneity is not correlated between loci, primarily due to an aberrant pattern of rate heterogeneity at nonsynonymous sites of rbcL. We compare patterns of synonymous rate heterogeneity to predictors based on the generation time effect and the speciation rate hypotheses. Although there is some evidence for generation time effects, neither generation time effects nor speciation rates appear to be sufficient to explain patterns of rate heterogeneity in the grass plastid sequences.      

Effect of biologically active splenic factors on the functional state of mast cells in rats]

The effects of "splenic protein-free extract" and its fractions as well as splenin on the functional activity of the rat mast cells have been studied. It is established that this extract unlike splenin has no histamine-releasing activity, however it is able to inhibit histamine release from mast cels under the influence of specific liberator--substance 48/80. The found effect is associated with biologically active substances contained in fraction III of splenic protein-free extract.     

The influence of diphosphonic analogues of inorganic pyrophosphate on reactions catalyzed by DNA-dependent RNA-polymerase II

Diphosphonic analogues of inorganic pyrophosphate were studied for their influence both on RNA pyrophosphorolysis and pyrophosphate exchange, catalyzed by purified DNA-dependent RNA-polymerase II from calf thymus. Methylene-, oxyethylene-and aminomethylenediphosphonic acids are shown to compete with PPi for incorporation into nucleoside triphosphate. They activate RNA pyrophosphorolysis in the concentration of 2 mM, but to a less extent than PPi does.     

Various physico-chemical properties of inorganic pyrophosphatase from the mouse spleen

Manganese, calcium and mercury ions, as well as p-chloromercury benzoate and dithiothreitol are studied for their effect on the activity of inorganic pyrophosphatase (EC 3.6.1.1) of mice spleen. It is shown that Ca2+ and Mn2+ are inhibitors of this enzyme, but Mn2+ in low concentrations may replace Mg2+ in the pyrophosphatase reaction. Hg2+ and p-chloromercury benzoate inhibit the pyrophosphatase activity essentially but not completely. Mice spleen pyrophosphatase is very labile: its preincubation without the substrate for 30 min at 37 degrees C leads to a complete loss of the activity. Neither glycerol, nor glutathione and cysteine but magnesium ions, dithiothreitol and 2-mercaptoethanol protect the enzyme from inactivation. The enzyme is purified by the sulphate ammonium salting-out, gel filtration on Sephadex G-100 as well as by isoelectrofocusing in 5% PAAG. Then pyrophosphatase is eluted from gel and subjected to electrophoresis in the plane layer of the linear gradient of 5-15% PAAG with SDS or 5-25% PAAG without denaturing conditions. One zone corresponding to the molecular mass of 70 kDalton is obtained. It is splitted into two zones in electrophoresis with SDS and 2-mercaptoethanol.     

Concentration of prostaglandins and cyclic adenosine-3',5'-monophosphate in the tissues of rats]

The content of prostaglandines (PG) and cyclic 3',5'-adenosine monphosphate (cAMP) was investigated in rat tissues by the radioisotopic method of competitive binding. Maximum quantities of both PG and cAMP were revealed in the same most actively functioning organs: the brain, incretory glands, small intestine. Fatty tissue showed minimum quantities of these substances. Results indicate a close functional relationship between the PG synthesis and adenylatecyclase activity in the body tissues.     

Minimal amino acid sequence, recognized by anibodies to the peptide GPQPPQPPQP from the proline-rich region of pertactin

Three antiserum samples obtained from rabbits immunized by the conjugate KLH-10P (keyhole limpet hemocyanine-decapeptide GPQPPQPPQP) were used to study antigenic structure of 10P. Antigenic properties of conjugates 6P (PGPQPP) and 4P (PQPP) with ovalbumine were studied by an indirect immunoassay (ELISA). Also 4P, 6P, PQP and QPP peptides were used for a competition assay. It was found that antibodies to 10P have demonstrated different specificity to short sites. Antibodies recognized such shot peptides as PQP and QPP in the competition assay. The efficiency of serum antibodies reaction with those peptides increased from QPP and PQP to PGPQPP. Only one serum sample had no antibodies to glutaraldehyde. Gly-glutaraldehyde-Gly hapten-like ligand was used to inhibit activity of antibodies to cross-linking agent into two samples. It is allowed to improve analysis of antibodies, which recognize shot sequences PQP and QPP.     

The role of calcium ions in fibrin polymerization

The article reviews the literature and authors' own data on the role of Ca ions in blood coagulation, namely, in the process of the formation of highly ordered fibrin clot. It has been shown that the main role of Ca2+ is the timely formation and stabilization of fibrin polymerization sites at all successive stages of the fibrin polymerization process.