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A L Berman

Publications and source records attributed to A L Berman.

90 records · Page 5Linked to original sources
PubMedDate not supplied

[The construction of an evolutionary tree for signal receptor proteins].

A method is suggested for evolutionary tree building for proteins with low level of similarity. The degree of similarity is computed by conservative parts for a given family. The method allows to reveal the relationship of amino acid sequences even in cases when conventional techniques yield negative results. Evolutionary tree for signal receptor proteins is built. All the investigated proteins (except STE2) display non-accidental similarity.

Amino Acid Sequence↗
PubMedDate not supplied

[A comparison of the cDNA of the sequences of signal receptor proteins].

The method of cDNA sequences comparison is suggested. The method consists of constructing the dot matrixes for each codon position separately. The fastest disappearance of the information about relationship is observed when the third nucleotides in codon are compared, and the comparison of the second nucleotides in codon turned out to be effective so as the comparison under acids.

Amino Acid Sequence↗
PubMedDate not supplied

[The evolution of signal receptor proteins: conserved regions and the similarity to GTP-binding proteins].

A sequence comparison of signal receptor proteins (SR) was carried out using computer techniques based on physicochemical characteristics of amino acids. A new method of conserved regions determination for a family of proteins is described. Visual pigments have four, and all SR--three such regions in the cytoplasmic loops. Possible functional significance of these regions is discussed. We also report here that the family of SR is similar with the family of G-proteins involved in extracellular signal transduction. Both families have similar regions consisting of 7-8 amino acids and a number of identical amino acids distributed on the considerable part of the polypeptide chain of the proteins. These facts may indicate that the whole ensemble of the proteins participating in transmembrane signalling pathways (or some part of it) could evolve from a common progenitor. At the same time, similar structure elements of members of the mentioned protein families my be functionally important for protein-protein interaction.

Amino Acid Sequence↗
PubMedDate not supplied

[G-proteins have a sequence similar to ganglioside-binding hemagglutinins from the influenza virus].

Local homology was found between a conservative region of the family of alpha-subunits of GTP-binding proteins and the ganglioside-binding site of influenza virus hemagglutinins. Both families of proteins have similar patterns of distribution of hydrophilic and hydrophobic amino acid residues. GTP-binding proteins and hemagglutinins are proposed to have a common molecular mechanism which underlies their attachment to cell membrane.

Amino Acid Sequence↗
PubMedDate not supplied

[Changes in the properties of photostimulated cyclic nucleotide phosphodiesterase from the retina of rats with hereditary retinal degeneration].

A degree of extractability and activation of cGMP-phosphodiesterase (PDE) (EC. 3.1.4.17) from the rod outer segment membranes was studied in Campbell rats with inherited retinal degeneration and control Wistar rats as compared to the control, the PDE extractability in the diseased rats was found to be considerably lower, which manifested as early as the 15th day of the postnatal life. Changes in the GTP-stimulated and basal PDE activity were observed in Campbell rats. Beginning from the 25th day of the postnatal life the GTP-stimulated PDE of degenerative retina decreased and by the 60th day it reached the basal activity level in these animals. In the diseased rats the first 57 days of postnatal life the basal activity of PDE was sufficiently higher, followed by a sharp decrease reaching the basal activity level of the control rats. The obtained data on the changed PDE activity are likely to be a result of the disturbance in the protein-lipid interaction and a change in the external layer of the photoreceptor membranes in rats with inherited retinal degeneration.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMedDate not supplied

[The similarity of the primary structure and homology of rhodopsin, beta-adrenoreceptor and muscarinic cholinoceptor].

Computer analysis has been made of the primary structure of 6 different types of receptor proteins: rhodopsin, adrenoreceptor, muscarinic acetylcholine receptor, insulin receptor, nicotinic cholinoreceptor, and bacteriorhodopsin. The aim of the present investigation was to elucidate, at least partially, to what extent insignificant similarity in the primary structure of rhodopsin, muscarinic cholinoreceptor and adrenoreceptor is due to divergent, but not convergent, evolution. Nicotinic cholinoreceptor, bacteriorhodopsin and insulin receptor were chosen for comparison with rhodopsin, adrenoreceptor and muscarinic cholinoreceptor since each of these proteins exhibits this or that structural or functional property which is common for rhodopsin, adrenoreceptor or muscarinic cholinoreceptor; on the other hand, nicotinic cholinoreceptor, bacteriorhodopsin and insulin receptor differ from other receptor proteins by their molecular mechanisms. Comparison of the primary structure of rhodopsin, adrenoreceptor and muscarinic cholinoreceptor on the one hand, and insulin receptor, nicotinic cholinoreceptor and bacteriorhodopsin on the other indicates that only the former exhibit similar primary structure, whereas insulin receptor, nicotinic cholinoreceptor and bacteriorhodopsin show no similarity neither in their primary structure, nor in the primary structure of rhodopsin and other receptor proteins which are similar to the latter with respect to their mode of action. The data obtained indicate that similarity in the primary structure between rhodopsin, muscarinic cholinoreceptor and adrenoreceptor is a consequence of divergent, not convergent, evolution; in other words, these receptor proteins are homologous.

Amino Acid Sequence↗
PubMedDate not supplied

[Preparative synthesis of 1,4,5-triphospho-SN-myo-inositol].

1,4,5-triphospho-sn-myo-inositol, widely investigated as a new second messenger, was prepared using phosphatidylinositol-specific phospholipase C of the bacterial origin. The methods of thin-layer chromatography are applied for the purification of hydrophilic products of phosphoinositides' hydrolysis.

Animals↗
PubMedDate not supplied

[Thermal stability of rhodopsins and opsins in warm- and cold-blooded vertebrates].

Thermal stability of rhodopsins and opsins has been studied in endothermic (sheep, cattle, pig, rat) and ectothermic (frog) animals under two different conditions -- in the intact photoreceptor membranes (PM) and after substitution of the lipid surrounding of rhodopsins by molecules of a detergent Triton X-100. Lipid composition of PM in these animals was also studied, as well as the effect of proteases (pronase and papaine) upon thermal stability of rhodopsins in PM and in 1% Triton X-100 solutions. The thermal resistance of rhodopsins in PM was found to vary in the animals used to a great extent. The maximal differences in thermal stability of rhodopsins in ecto- and endothermic animals were due to the properties of photoreceptor protein itself, whereas in ectothermic animals they resulted mainly from differences in the lipid composition of PM. PM of endothermic animals differ from those of ectothermic ones by a lower content of polyenoic fatty acids and by a higher amount of phosphatidyl ethanolamine. The thermal stability of rhodopsins is not due to rhodopsin molecule as a whole, and depends mainly on its part which is directly bound to 11-cis retinal, located in hydrophobic region of PM and inaccessible to protease attack.

Animals↗
PubMedDate not supplied

[Cooperative binding of calcium ions by photoreceptor membranes].

Equilibrium calcium binding by photoreceptor membranes of cattle retina in 5 mM tris-HCl buffer, pH = 7.4 at 5 degrees C in concentration interval from 2 X 10(-7) M to 2 X 10(-3) M has been studied. Binding of Ca2+ was found to depend on the manner of photoreceptor membranes preparation. Cooperative effect of Ca2+ binding in concentration interval from 2 X 10(-7) M to 10(-5) M was observed.

Animals↗
PubMedDate not supplied

[Fatty acid composition of the bilayer phospholipids in the photoreceptor membranes and aminophospholipids from the rhodopsin microenvironment of warm-blooded and cold-blooded vertebrates].

Studies have been made on the distribution of phospholipids between rhodopsin and free lipids of photoreceptor membranes of the outer segments of retinal rods from cattle, frog Rana temporaria and fish Teragra chalcogramma. comparative investigation of fatty acid composition of phospholipids from rhodopsin microboundary and lipid bilayer in photoreceptor membranes was made as well. Amino phospholipids from rhodopsin microboundry were revealed using glutaraldehyde. This reagent by means of its aldehyde groups links phospholipid amino groups with amino groups of proteins of photoreceptor membranes. After this treatment, free phospholipids of lipid bilayer were extracted from photoreceptor membranes by methanol-chloroform mixture. It was demonstrated that fatty acid composition of phospholipids of lipid bilayer differs from that of amino phospholipids from rhodopsin microboundary. In the animals investigated, fatty acids of phospholipids from lipid bilayer were found to be more unsaturated than fatty acids of amino phospholipids from rhodopsin microboundary. This difference was more pronounced in photoreceptor membranes from the frog and fish than from cattle.

Animals↗
PubMedDate not supplied

[Modification of the retina photoreceptor membranes and temperature stability of rhodopsin].

The effect of modification of photoreceptor membranes of the bovine retina on the termodynamical parameters that characterize heat denaturation of rodopsin was studied. The highest increase of the rate constant and the corresponding maximal drop of the free energy change of heat denaturation of the pigment were obtained by using 7 M urea or 25% Triton X-100 in the presence of 5.10(-4) M EDTA. After chipping off one third of the protein from the rodopsin molecule by papain treatment a significant decrease of the slope of the Arrenius curve and a maximal decrease of entropy change compared to the parameters known for heat denaturation of the pigment in native photoreceptor membranes were found. Modification of the lipid components of the photoreceptor membranes (treatment with Triton X-100 and phospholipase C) reduced the thermostability of rodopsin. Maximal changes were obtained at Triton X-100 concentrations 0.1--1%, further concentration increas (1--25%) did not lead to significant changes. Phospholipase C treatment resulted in a decrease of free energy change and an increase of entropy change without affecting entalpy changes, accompaning the heat denaturation of rodopsin. Bivalent cations (Ca2+, Mg2+) increased the termostability of rodopsin both in photoreceptor membranes and in solutions to 25% Triton X-100.

Animals↗
PubMedDate not supplied

[Thermostability of the rhodopsins of several fish in the Sea of Japan].

Studies have been made on thermal denaturation of rhodopsin in hotoreceptive membranes of retinal rods of some Japan Sea fishes--Podthecus sp., Enophrys diceraus, Myoxocephalus stelleri, Pleurogrammus monopterygius, Sebastichthys trivittatus, Pheumatophorus japonicus, Gadus morhua, Theragia chaloogramma, Eleginus gracilis and Lepidopsetta herzensteini. It was shown that visual pigments of the species studied significantly differ in their thermostability, whereas with respect to their spectral properties they are rather similar (absorbtion maxima lie near 500 nm). Positive correlation between the thermostability level of rhodopsins and the environmental temperature of the species was found.

Adaptation, Physiological↗