Biomedical subjects

S Puszkin

Publications and source records attributed to S Puszkin.

At least 73 records · Page 4Linked to original sources

PubMed1979

The role of cytoskeleton in neuron activity.

The extensive cytoskeleton present in brain tissue is composed of microfilaments, neurofilaments, and neurotubules. A clear understanding of each of these structures is required to accurately define their participation in neuronal functions. Until more is known, therefore, we are restricted to speculate on their importance to the general activity of the cell. The presence of microfilamentous proteins in nerve endings -- the sites where nerve transmission is chemically sustained -- strongly suggests their participation in the release of putative neurotransmitters, a hypothesis that may be substantiated in the near future. It follows that alteration in assembly, disassembly, or interaction among the various cytoskeletal components may permit some insight into the causes and origins of a variety of neurological alterations affecting humankind.

Animals↗

PubMed1978

Erythrocyte actin and spectrin. Interactions with muscle contractile and regulatory proteins.

Actin and spectrin were isolated from washed red blood cell membranes. Spectrin bound and polymerized erythrocyte actin in the absence of potassium. Spectrin coated into polystyrene latex particles bound 8--9 mol of erythrocyte actin per mol of spectrin when actin was in its depolymerized state. Spectrin enhanced the interaction of erythrocyte actin with muscle myosin as manifested by changes in Mg2+-ATPase activity. A similar enhancement also was observed with muscle alpha-actinin while muscle tropomyosin abolished these effects. The data suggest that spectrin may play the role of polymerizing factor as well as the anchoring site for erythrocyte actin just as alpha-actinin is the anchoring site for actin filaments in muscle and other non-muscle cells.

Actinin↗

PubMed1978

Isolation and properties of brain alpha-actinin.

alpha-Actinin isolated from bovine brain migrated on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis like muscle alpha-actinin with an apparent mol.wt. of 100000 and cross-reacted with antibodies to muscle alpha-actinin. Brain alpha-actinin modulated actin-myosin Mg2+-activated adenosine triphosphatase activity and, when bound by polystyrene particles, was found to bind muscle actin and tropomyosin from solution. Brain alpha-actinin, in conjunction with the other components of the contractile and relaxing complex, may play a role in the release of neurotransmitters from synaptic vesicles.

Actinin↗

PubMed1978

Erythrocyte troponin inhibitor-like protein: isolation and characterization.

A protein was isolated from a human erythrocyte lysate with an apparent molecular weight of 23,000--24,000 daltons. This protein was purified by batch DEAE cellulose followed by column DEAE cellulose chromatography and a gradient of NaCl. On sodium dodecyl sulfate acrylamide electrophoresis, the erythrocyte protein comigrated with muscle troponin inhibitor. An isoelectric precipitation (pH 9.25) was used for the separation of muscle troponin inhibitor from a complex with another troponin component. Both the erythrocyte protein and the muscle troponin inhibitor partially inhibited muscle myosin Ca2+ and K+-EDTA ATPase activity. Furthermore, they inhibited actin-activated Mg2+-ATPase of muscle myosin. The inhibitory effects were absent in the presence of muscle troponin calcium-binding component. Muscle troponin inhibitor and the erythrocyte troponin inhibitor-like protein bound to muscle myosin when myosin was precipitated twice at low ionic strength. The presence of a troponin inhibitor-like protein in erythrocytes suggests that it may be a component in the regulation of contractile activity.

Actins↗

PubMed1977

Immunological identification of complex proteins resolved by sodium dodecyl sulfate polyacrylamide disc gel electrophoresis.

Immunological identification of an antigen resolved from a protein complex by sodium dodecyl sulfate polyacrylamide gel electrophoresis has been attained. The identification is based on the formation of immunoprecipitin lines after the antigen diffuses laterally from acrylamide gel transverse slices into a surrounding agarose gel. This technique was designed for study of contractile and regulatory protein complexes of non-muscle cells where the scarcity of tissue precludes easy purification or high yield of muscle-like proteins. It complements double-gel immunodiffusion or immunoelectrophoresis and its use may be extended to other protein complexes.

Actinin↗

PubMed1977

alpha-Actinin and tropomyosin interactions with a hybrid complex of erythrocyte-actin and muscle-myosin.

alpha-Actinin isolated from dog muscle was used to incite antibodies in rabbits, Antibodies, purified by affinity chromatography on CNBr-Sepharose coupled with alpha-actinin and then ferritin-labeled were found to localize on the Z disc of muscle sarcomeres. Molecules of alpha-actinin as an adsorbed monolayer on the surface of polystyrene Lytron particles could bind muscle-actin and tropomyosin from solution. Both the ATPase activity and superprecipitation of an erythrocyte-actin and muscle-myosin hybrid actomyosin complex were altered by alpha-actinin, while tropomyosin diminished these alpha-actinin effects. The binding properties of alpha-actinin are consistent with those of an anchoring protein for microfilaments in nonmuscle cells.

Actinin↗

PubMed1976

Muscle damage produced by chronic alcohol consumption.

The effects of chronic alcohol consumption on skeletal muscle, independent of nutritional factors, were studied. Chronic alcohol ingestion led to striking ultrastructural changes in skeletal muscle, including intracellular edema, enlarged and distorted mitochondria, dilatation of sarcoplasmic reticulum, and increased amounts of fat and glycogen. Actomyosin was isolated from skeletal muscle of baboons and volunteers fed alcohol. In this preparation, ATPase activity and the calcium sensitivity of ATPase were decreased. The isolated actomyosin displayed reduced contractility in vitro, measured by the association of actin and myosin and the response to adenosine diphosphate (ADP). In 2 of 3 volunteers, isolated membranes of the sarcoplasmic reticulum exhibited decreased calcium uptake. The pressure-rate product was increased in some of the volunteers after submaximal or maximal work. The changes decribed in this study were found after alcohol administration had been discontinued, and they may play a role in the development of alcoholic myopathy and cardiomyopathy.

Actomyosin↗

PubMed1975

Adenosine diphosphate effect on contractility of human muscle actomyosin: inhibition by ethanol and acetaldehyde.

Magnesium adenosine triphosphate (Mg-2+-ATP) is known to produce dissociation of muscle actin and myosin in vitro, while its hydrolysis leads to reassociation. The interaction of purified actin and myosin from human muscle, in the presence of Mg-2+-ATP, was stimulated by minute amounts of adenosine diphosphate (ADP), a product of ATP hydrolysis. By contrast, the dissociation of the actomyosin complex was inhibited by ADP. These data suggest that ADP serves to modulate muscle contraction. Ethanol and its primary metabolite, acetaldehyde, inhibited these effects of ADP. The inhibition was reversible when the preparations were freed of these compounds. The effects of ethanol and acetaldehyde on the response of actomyosin to ADP may play a role in the pathogenesis of alcoholic myopathy and cardiomyopathy.

Acetaldehyde↗

PubMed1975

A solid-liquid biphasic model for characterization of properties of muscle and platelet contractile proteins.

Actomyosin, myosin, and actin from different sources are adsorbed, apparently as a monolayer, by polystyrene particles teins for 1 mg of Lytron were about 10-7 liters mol-1, while heterogeneity indices (alpha) varied from 0.70 to 1.0 presumably as a function of spontaneous aggregation in the liquid phase. Adsorption was irreversible. Orientation of absorbed molecules permitted association of bound muscle actin with platelet or muscle myosin. The association constant of the former reaction was 2.78 times 10-6 liters mol-1. Enzymatic properties of adsorbed actomyosin, Mg2+ATPase activity was abolished, but association of myosin with bound actin, or association of actin with bound myosin was accompanied by restoration of Mg2+ATPase activity. Every subunit of F-actin strands, unless F-actin had been fully depolymerized to G-actin, could bind myosin and activate Mg2+ATPase activity. Immunogenic characteristics of muscle myosin were enhanced by Lytron adsorption. Elicited antibodies showed selective specificity for an antigenic determinant located near or at the actin combining site of muscle myosin. Antibodies did not react with actomyosin. Antibodies prevented association of actin with muscle myosin because they inhibited both superprecipitation and development of Mg2+ATPase activity.

Actins↗

PubMed1974