Properties of the regulatory subunit of cAMP-dependent protein kinase type II from human brain.

The regulatory subunit type II (RII) of cAMP-dependent protein kinase purified from human brain was represented by two proteins with apparent molecular masses of 51-52 kD and 54 kD. Dephosphorylation of human RII containing 3 mol phosphate/mol protein did not change the electrophoretic pattern. One-dimensional peptide mapping of 51-52 kD and 54 kD proteins after digestion with St. aureus V8 protease evidenced to their being distinct proteins. The data obtained permit to assume that human RII of neural type is represented by two isoforms.

Immunochemical studies on human, bovine and pig brain regulatory subunits of cAMP-dependent protein kinase type II.

Regulatory subunits type II (RII) purified from human, pig and bovine brains were compared using II monoclonal antibodies (MoAb) against bovine brain RII. Bovine RII has at least 5 antigenic sites located in the N-terminal 1-110 residues. Immunochemical difference detected between human and animal RII was more pronounced than between pig and bovine RII. Certain MoAb influenced R-cAMP binding and holoenzyme formation. RII of the three species responded to MoAb attachment in a similar fashion. The results suggest that anchoring of neural protein kinase via the N-terminal part of RII may influence the enzyme activity.

Antibodies to the regulatory subunit of cAMP-dependent protein kinase type II from bovine brain inhibit the holoenzyme formation.

Mouse monoclonal antibodies to the bovine brain regulatory subunit type II (RII) were produced and antibodies of 11 clones were characterized. We determined their subclass, affinity constants, competivity and influence on two RII functions, namely cAMP binding and inhibition of the catalytic subunit (C) activity. 4 clones produced antibodies that increased RII-cAMP binding 1,5-2-fold. Antibodies of other 3 clones prevented R-C association and inhibition of C phosphotransferase activity. Some antibodies affected neither of these RII functions.

[Immunochemical properties of the regulatory subunit of cAMP-dependent protein kinase II]. / Immunokhimicheskie svoistva reguliatornoi sub''edinitsy cAMP-zavisimoi proteinkinazy II tipa.

Immunochemical analysis of the cAMP-dependent protein kinase regulatory subunit type II was performed with the use of two rabbit antisera elicited to a free R-subunit from pig brain and to a RcAMP complex. Quantitative precipitation of the homogeneous antigen revealed six determinants on the R-molecule. Of these at least one is localized in the R-fragment (37 kD), the others--in the N-terminal part of the R-molecule. The antigenic determinants seem to be remoted from the cAMP-binding centers, since the attachment of the affinity purified antibody Fab-fragments to the R-subunit did not influence the cAMP-binding activity of the latter. The antibodies to RcAMP caused dissociation of the holoenzyme. The antibody Fab-fragment binding to the R-subunit prevented its association with the catalytic subunit. The results of immunochemical analysis suggest that the R-subunit adopts different conformations when bound to cAMP or to the catalytic subunit.

[The enhanced relative intensity of cAMP-dependent protein phosphorylation in stomach tumors]. / Uvelichenie otnositel'noi intensivnosti cAMP-nezavisimogo fosforilirovaniia belkov v opukholiakh zheludka.

The activity of cAMP-dependent histone kinases (HK) and cAMP-independent casein kinases (CK) as well as cAMP level were assessed in gastric mucosa affected by various forms of gastritis as well as in gastric tumor and adjacent normal tissue. CK activity was higher whereas that of HK and cAMP level were lower in tumor and at a distance of 5-20 cm from its edge as compared to gastritis. CK/HK cAMP ratio in adenocarcinoma was 6 times that in normal tissue and 2-2.5 times that in gastritis. The data obtained and those published earlier suggest the relative increase in cAMP-independent protein phosphorylation with respect to its cAMP-dependent counterpart to be characteristic of human tumors.

[Protein kinase activity and cAMP level in gastric mucosa in non-neoplastic diseases]. / Aktivnost' proteinkinaz i soderzhanie cAMP v slizistoi obolochke zheludka pri neopukholevykh zabolevaniiakh.

Activity of cAMP-dependent and -independent protein kinases as well as content of cAMP were studied in biopsy preparations of gastric mucosal membranes obtained from patients with superficial gastritis, erosion, ulcer, adenomatous polyps and ulcer after treatment with laser irradiation. All the patterns studied were similar in preparations of adenomatous polyps and normal mucosal membrane. Activity of cAMP-independent protein kinases was increased under conditions of erosion, ulcer, gastroduodenal reflux and, especially, in ulcer tissue treated with laser. However, the ratio between cAMP-independent and -dependent phosphorylation was increased only in 50% of ulcerous diseases and in gastroduodenal reflux. The equilibrium of cAMP-dependent and -independent phosphorylation was not altered in the other impairments studied even though benign proliferation was stimulated using laser irradiation.

[Identification of serotonin receptors in several grape snail neurons]. / Identifikatsiia serotoninovykh retseptorov na nekotorykh neironakh vinogradnoi ulitki.

Four types of unit responses to iontophoretical serotonin (5-hydroxytrytamine) application were obtained on the ventral surface of the visceral ganglion in the hibernating Helix pomatia. The responses differed in sign, duration, latent period, reaction to serotonin antagonists (d-tubocurarine, tryptamine, neostigmine). It seems that every type of unit response to serotonin is associated with a definite type of serotonin receptors. A scheme of serotonin receptor distribution in the studied neurons is presented.