Endomembranes and vesicle trafficking.

Over the past year extensive analyses of the accumulated data on the structural and functional organisation of the endomembrane system and vesicular trafficking in higher plants have shown it to be far more complex than previously anticipated. The availability of molecular tools combined with new opportunities to visualise endomembrane dynamics in vivo will allow better understanding of the fundamental processes underlying the complexity of endomembrane behaviour and vesicular trafficking.

RdgC/PP5-related phosphatases: novel components in signal transduction.

A great variety of cellular functions are regulated by protein serine/threonine phosphatases (PP). This review summarises the current knowledge of the structural features, patterns of expression and involvement in signal transduction pathways of protein serine/threonine phosphatases related to PP5 and RdgC. Designated now as PP5/RdgC subfamily by P.

[Ser/Thr-phosphatases from bovine retina: detection of cDNA coding for the catalytic subunit of the gamma-isoform PP2B and two homologs of rdgC/PPEF].

The expression of genes for Ser/Thr phosphatases of the PP1/2A/2B class in the bovine retina was analyzed using PCR on cDNA. The mRNAs were found for the following phosphatases: PP1 (alpha- and gamma-isoforms), PP2A (alpha- and beta-isoforms), PPV, and PP2B (beta- and gamma-isoforms). Earlier, PP2B gamma-isoform was considered testis-specific.

Non-classical protein Ser/Thr phosphatases: what are they for?

Protein serine/threonine phosphatases are involved in regulation of diverse cellular functions. This review is devoted to a novel group of protein Ser/Thr phosphatases, rdgC/PP5, which has been recently discovered in animals, fungi, and plants. Their structure, location, and possible functions are discussed.

Proteins involved in membrane transport between the ER and the Golgi apparatus: 21 putative plant homologues revealed by dbEST searching.

Numerous proteins have been identified in yeast and mammalian cells which are involved in trafficking between the endoplasmic reticulum and the Golgi apparatus. A great number of partial cDNA sequences now available from the two major plant model species, Arabidopsis thaliana and Oryza sativa, makes it possible to identify putative plant homologues of known genes/proteins from non-plant species. The authors used this approach to screen the database of Expressed Sequence Tags (dbEST) in order to detect plant homologues of proteins involved in membrane transport between ER and Golgi.

Expression and characterization of PP7, a novel plant protein Ser/Thr phosphatase distantly related to RdgC/PPEF and PP5.

We have recently identified an Arabidopsis thaliana cDNA encoding a putative protein Ser/Thr phosphatase PP7, not closely related to any protein phosphatases in animals or fungi. Here, we describe the characterization of PP7 expressed in a bacterial system. The recombinant protein was inactive unless the longest insert in its catalytic domain was cleaved, suggesting that this insert is an autoinhibitory region.

The extracellular domain of CD4 receptor possesses a protein kinase activity.

The CD4 receptor of T-helper cells is an essential participant in immune response formation and HIV infection. We report here that the extracellular domains of CD4 receptor can catalyze the phosphotransferase (kinase) reaction. Incubation of rsCD4 in solution with [gamma-32P]ATP results in the Ca2+-dependent autophosphorylation of the protein presumably at a His residue because the reaction is prevented by the diethylpyrocarbonate treatment.

PP7, a plant phosphatase representing a novel evolutionary branch of eukaryotic protein Ser/Thr phosphatases.

We describe a novel protein Ser/Thr phosphatase from Arabidopsis thaliana, PP7, which is only 27-32% identical in amino acid sequence to the known phosphatases and is the most divergent member of the PPP (PP1/2A/2B) family for today. Some structural features suggest more close relationship of PP7 to the PP5/rdgC subfamily. PP7 contains all of the residues essential for the phosphatase activity and possesses three major insertions in its presumable C-terminal subdomain, which suggest its unique regulation and/or optimisation of its structure for interaction with specific substrates or regulators.

[Genes of plant Ser/Thr protein phosphatases: detection of sequences related to PPT/rdgC].

An unknown sequence that may encode a fragment of the Ser/Thr protein phosphatase (designated PP6Zm) related to PPT/rdgC phosphatases was identified using PCR on maize genomic DNA. A dbEST search using a partial amino acid sequence of PP6Zm revealed a putative homolog of PP6Zm expressed in Arabidopsis thaliana (EMBL AT6726). A search of the SwissProt database indicated that the partial amino acid sequence of AT6726 has the highest identity (54.

[Cloning and expression of cDNA for tobacco rab1, and structural-functional analysis of the protein].

rab1 cDNA coding for a small GTP binding protein Rab1 was isolated from cDNA library of tobacco (Nicotiana tabacum) leaves. The primary structure of this protein was deduced from the rab1 structure. Tobacco rab1 cDNA was expressed in Escherichia coli, and the product was purified and shown to exhibit GTPase activity.

Regulation of rDNA transcription in chloroplasts: promoter exclusion by constitutive repression.

Spinach chloroplasts contain two types of RNA polymerases. One is multimeric and Escherichia coli-like. The other one is not E.

[Pathogenetic mechanisms of the so-called astronauts' anemia].

The authors analyze the literature data published in the last 20 years on clinical, laboratory, physiological, hematological and biochemical evidence obtained at preflight and postflight examinations of astronauts and experimental animals who spent 5-12 months in space. After space flights the astronauts exhibited a noticeable decrease in red cell mass, in reticulocyte count, hemoglobin and erythropoietin levels (associated with hypochromia and hyposideremia). This condition of erythron in microgravity is termed astronauts' anemia.

Structure of the 265-kilodalton complex formed upon EDC cross-linking of subfragment 1 to F-actin.

The conventional model of force generation in muscle requires the presence of at least two different contact areas between the myosin head (S1) and the actin filament. It has been found that S1 has two sites available for carbodiimide cross-linking, but it is generally believed that the myosin head can be cross-linked to only one actin through either site. We provide here, for the first time, evidence that one S1 can be cross-linked to two separate actin molecules.

Two different rigor complexes of myosin subfragment 1 and actin.

Our previous titration and cross-linking experiments showed that myosin subfragment 1 (S1) can bind to one or two monomers in F-actin [Andreev, O. A., & Borejdo, J.

Polarization of fluorescently labeled myosin subfragment-1 fully or partially decorating muscle fibers and myofibrils.

Fluorescently labeled myosin heads (S1) were added to muscle fibers and myofibrils at various concentrations. The orientation of the absorption dipole of the dye with respect to the axis of F-actin was calculated from polarization of fluorescence which was measured by a novel method from video images of muscle. In this method light emitted from muscle was split by a birefringent crystal into two nonoverlapping images: the first image was created with light polarized in the direction parallel to muscle axis, and the second image was created with light polarized in the direction perpendicular to muscle axis.

[Study of the nature of determinants for synthesis of delta-endotoxin and beta-exotoxin in Bacillus thuringiensis subsp. thuringiensis strains--bitoxybacillin producers].

The growth of Bacillus thuringiensis subsp. thuringiensis strains (BT) 202, 1140, 98 producing bitoxybacillin in the presence of novobiocin, mitomycin C and at high temperature 43 degrees C resulted in obtaining of the mutants for the synthesis of crystalline protein (Cry) and exotoxin (Exo). Analysis of the plasmid content of the mutants has shown the Cry Exo phenotyre to correlate with the loss of 55 MD plasmid in the strain BT202 and the loss of 60MD plasmid in BT1140.

[Indicators of iron metabolism in pregnant women and infants].

Iron metabolism parameters were studied in pregnant women in time course of trimesters depending on the pregnancy character and in newborns and infants in relation to the antenatal period. The dynamic study of serum and erythrocytic ferritins has confirmed the expediency of iron therapy during pregnancy for prevention of iron deficiency in infants. Differences detected in the rate of using iron reserves by infants of the first year of life depending on the antenatal period character have necessitated an individual approach to preventive iron therapy.

[Plasmids for biodegradation of 2,6-dimethylpyridine, 2,4-dimethylpyridine, and pyridine in strains of Arthrobacter].

Arthrobacter crysallopoietes strain KM-4 degrading 2,6-dimethylpyridine and strain KM-4a degrading both 2,6-dimethylpyridine and pyridine, Arthrobacter sp. KM-4b degrading 2,4-dimethylpyridine were isolated from soil. Arthrobacter crystallopoietes KM-4 and Arthrobacter sp.

[Iron metabolism in anemia patients with no deficiency of iron reserves].

Iron metabolism was studied in anemia patients with no iron deficiency. The data obtained have suggested that iron transport to blood-synthesizing cells i disturbed in such patients with normal iron reserves. Basing on the study of iron metabolism and red blood parameters in the patients after the treatment by hypoxic hypoxia it is shown that this method combined with iron therapy can be successfully used for the treatment of this form of iron deficiency anemia.