The binding of cGMP by structural components of bovine rod outer segments was studied. The discs and plasma membranes were shown to contain two types of the specific binding sites for cGMP which are distinct from cyclic GMP phosphodiesterase. The sites have a "high" and "low" (Kd = 0.1 divided by 0.35 and 1.5 divided by 2.0 X 10(-6) M respectively) affinity for cGMP. They belong to membraneous integral proteins presumably associated with phospholipids. Their affinity for cGMP is controlled by GTP and calmodulin.

Animals↗

PubMedDate not supplied

[Effect of chlorpromazine on the relation between temperature and the binding of ANS by human erythrocytes].

It has been shown that under the effect of chlorpromazin (concentration to 2.10(-5) M) breaks observed on Arrhenius graphs of the rate constant of ANS binding with erythrocytes (k) at 28 and 36 degrees C are shifted to the region of low temperatures approximately to a similar interval (14-15 degrees C). The value k measured at 22 degrees C is not changed within the pH range of 5-7. It is concluded that breaks characterised the initial and final stages of temperature transition initiated in the zone of acid phospholipid of membranes.

Anilino Naphthalenesulfonates↗

PubMedDate not supplied

[Thermal transitions in erythrocyte membranes revealed by their permeability to ANS].

A number of breaks were recorded on the curve of Arrhenius relationship of the rate constant of the dye 1-anilino-8-naphthalenesulphonate sodium salt (ANS) input into human erythrocytes of 20, 28, 36, 42 and 46 degrees C. Variations in the values of activation energies within the temperature range of 28-36 degrees and 42-46 degrees C obtained in various blood samples allow to consider these temperatures as those at which structural changes of the membranes take place. The values of activation energy of the process for temperature "conformers" of the erythrocyte membrane are 12(10-20 degrees C), 26.5 (20-28 degrees C), 34.2(36-42 degrees C) and 47 kcal/mol (t is greater than 46 degrees C). Within the temperature range of 28-36 degrees and 42-46 degrees C an irreversible decrease of permeability to ANS of the erythrocyte ghost after their incubation for 10 min at increased temperatures were observed. Thus the temperature regions of the change in erythrocyte permeability correspond to those at which the resealing of ghost takes place. The break in Arrhenius graph at 20 degrees C seems to characterize a highly cooperative "point" transition. The lipid nature of the initiator of structural transition within 28-36 degrees C is proved by a sharp increase of the permeability of liposomes prepared from erythrocyte membrane lipids to ANS at 28 degrees C. The nature of the initiators of two other thermal transitions is discussed.

Anilino Naphthalenesulfonates↗

PubMedDate not supplied

[Cyclic GMP-induced structural transitions of photoreceptor membranes].

The influence of cyclic GMP on the structural state of photoreceptor membranes was studied. The spin probe technique was used to obtain the dependences of microviscosity of lipid domains of membranes on cGMP concentration. It was shown that microviscosity of 5-doxylsteraric acid environment in rod outer segment, disc and plasma mambranes changed at concentrations of 2.10(7); 5.10(-6) and 6.10(-6). Non-cyclic GMP was ineffective. The ultrasound treatment of membraneous samples resulted on disappearance of the structural changes.

Animals↗

PubMedDate not supplied

[Effect of falloidin on permeability of intercellular channels for inorganic ions and fluorescein].

It has been shown on larva gland that falloidin - a toxic of toadstool inducing an increased number of membrane microfilaments-affects the efficiency of intercellular transfer of small inorganic ions and molecules of organic dye fluorescein-Na. The data obtained are in favour of the participation of microfilaments in the regulation of intercellular diffusion communication.

Animals↗