Sequencing the erbA gene of avian erythroblastosis virus reveals a new type of oncogene.

Avian erythroblastosis virus (AEV) contains two distinct oncogenes, erbA and erbB . The erbB oncogene, which is homologous to a portion of the epidermal growth factor receptor, is related to the src family of oncogenes and efficiently transforms erythroblasts, whereas erbA potentiates the effects of erbB by blocking the differentiation of erythroblasts at an immature stage. This "potentiator" was sequenced; the amino acid sequence deduced from it was clearly different from the sequences of other known oncogene products and was related to carbonic anhydrases.

Differential reduction of the inter-chain disulfide bonds of rat immunoglobulin E: relation to biological activity.

Monoclonal rat IgE was reduced over a range of dithiothreitol (DTT) concns. The number of disulfide bonds reduced and their location in the IgE molecule were studied. One millimolar DTT was found to split the two inter-heavy-chain disulfide bonds of the C epsilon 2 domain while increasing DTT concn to 10 mM split the two inter-heavy-light-chain disulfide bridges.

[Characterization of L-threonine deaminase activity of guinea pig liver induced by a high protein diet].

In a foregoing paper, we demonstrated that under equilibrated diet conditions, guinea pig liver L-threonine deaminase activity should be allocated to two distinct enzymes: a specific L-threonine deaminase without activity toward L-serine and a L-serine deaminase having a secondary activity toward L-threonine. In the present work, we observed that a high protidic diet caused an elevation of total threonine deaminase activity. Thus purification of guinea pig liver L-threonine deaminase was attempted, using ultracentrifugation, salt precipitation, heat treatment, ion exchange chromatography on DEAE Sephacel, Sephadex G 200 molecular sieve, 2 amino-2 methyl-1 propanol linked CH 4B Sepharose chromatography.

Proteolysis of rat IgG subclasses by Staphylococcus aureus V8 proteinase.

Monoclonal IgG belonging to the four rat IgG subclasses (IgG1, IgG2a, IgG2b, IgG2c) and some IgG subclasses from normal rat serum were subjected to enzymatic degradation with Staphylococcus aureus V8 proteinase. The results show that only one subclass, IgG2b, is significantly cleaved by the enzyme, with the release of two main products identified as F(ab)2 and Fc-like fragments. This unique susceptibility of the IgG2b subclass represents therefore an easy means of identification and also offers a simple procedure for a preparation of F(ab)2 fragments from monoclonal IgG2b antibodies.

Formation of biologically inactive polymers is responsible for the thermal inactivation of rat IgE.

The structural changes induced by heating rat IgE at 56 degrees C and relationship with loss of cytotropic activity were examinated in the present study. Circular dichroism spectrum of IgE heated at 56 degrees C showed irreversible changes in the peptide bond spectral regions: increase in beta-sheet structure, but no significant modifications in the aromatic side chain region. Thus, circular dichroism studies did not suggest important perturbations of the tertiary structure of the IgE molecule.

Phylogenetic studies of cardiac myosins from amphibia to mammals.

Comparison between pig atrial and ventricular myosins was performed on the light chains (using SDS-PAGE) and on the heavy chains (using Ca2+-ATPase measurements and NTCBA peptide mapping). Light chain composition of pig cardiac myosins was compared to three other species ones (frog, chicken and human). Up to birds, atrial and ventricular myosin light chain composition was identical whereas in mammals atrial and ventricular myosin light chain composition was different; likewise the heavy chains.

63Ni[II]-incorporation into lung and liver cytosol of Balb/C mouse. An in vitro and in vivo study.

The kinetic studies of 63Ni[II]-incorporation in whole tissue show that after 6 days lung has the highest affinity to nickel of all studied organs. The same observation was made when 63Ni[II]-incorporation was carried out by 7 daily injections. In both experiments, kidneys take the second place in the relative distribution of nickel.

The amino-acid sequence of histone H2A from cuttlefish Sepia officinalis.

The amino acid sequence of cuttlefish testis histone H2A (124 residues) was established from structural data obtained by automated sequencing of large peptides generated by the cleavage of the protein with V8 staphylococcal protease or by limited chymotryptic hydrolysis. Compared to the calf thymus homologous histone, cuttlefish H2A shows 14 substitutions (most of them conservative) and 5 deletions. Extensive evolutionary changes were mainly observed in the basic amino-terminal and carboxy-terminal regions of the molecule, which are the primary DNA-binding sites.

UV differential study of the histones H2A-H2B-H3-H4 octamer.

The individual calf thymus histones H2A, H2B, H3 and H4, the dimer H2A-H2B, the tetramer (H3-H4)2 and the octamer (H2A-H2B-H3-H4)2 were studied by differential UV absorption i.e. observing absorption shifts of tyrosyl residues due to thermal perturbations.

Tryptic cleavage of rat IgG: a comparative study between subclasses.

Monoclonal rat IgG belonging to the 4 rat IgG subclasses, and some IgG subclasses isolated from normal rat serum were subjected to enzymatic degradation with trypsin. Differences in the products of tryptic digestion were observed according to the IgG subclass. IgG2b and IgG2c were degraded mainly into Fab and Fc fragments.

Flow cytofluorometric analysis of the effects of new nitrosourea derivatives on proliferation of EMT 6 tumor cells "in vitro".

Examined by flow cytofluorometric analysis, the DNA distribution of EMT 6 tumor cells was highly perturbed after one hour of in vitro incubation with: RPCNU, RFCNU, chlorozotocin (CZT) or 185 (CNCC), four new nitrosourea derivatives. After the treatment with chlorozotocin (20 micrograms/ml) and CNCC (50 micrograms/ml), most of cells were in G2 + M phase and this accumulation lasted more than 48 hours without any restoration before 72 hours. RPCNU (20 micrograms/ml) and RFCNU (50 and 65 micrograms/ml) induced and accumulation of cells in G2 + M phase during 24 hours.

Study of the 10-nm-filament fraction isolated during the standard microtubule preparation.

The cold non-depolymerizable fractions obtained during the standard procedure for the isolation of microtubules from ox brain stem-cerebral hemispheres and spinal cord have been studied. The cerebral-hemisphere preparation was composed of 10-nm filaments but also contained large amounts of membranes. The polypeptide content included tubulin, microtubule-associated proteins and minor proteins corresponding to the neurofilament triplet of proteins of mol.

Perineal rhabdomyosarcoma in a newborn child: pathological and biochemical studies with emphasis on contractile proteins.

Histological and ultrastructural studies have been undertaken on a perineal rhabdomyosarcoma from a newborn child. The spontaneous tumour has the typical feature of mesenchymoma. The recurrent tumour, however, displays some rhabdopoietic characteristics.

Direct analysis of the lectin reactivity of alpha-fetoprotein in maternal serum by crossed affinity radio-immunoelectrophoresis.

Affinity experiments with the lentil (Lens culinaris) lectin have revealed the existence of two distinct molecular populations of alpha-fetoprotein: lectin reactive and lectin non-reactive. Using a combination of crossed lectin immunoelectrophoresis and radio-immunoelectrophoresis, it has been possible to obtain directly the lentil lectin affinity patterns of alpha-fetoprotein present in maternal sera. The lentil lectin reactivity of maternal alpha-fetoprotein decreases almost linearly with the gestational age from week 15 to 35.