Identification of a 42-kilodalton phosphotyrosyl protein as a serine(threonine) protein kinase by renaturation

1990 ◽  
Vol 10 (6) ◽  
pp. 3020-3026
Author(s):  
J E Ferrell ◽  
G S Martin

We have surveyed fibroblast lysates for protein kinases that might be involved in mitogenesis. The assay we have used exploits the ability of blotted, sodium dodecyl sulfate-denatured proteins to regain enzymatic activity after guanidine treatment. About 20 electrophoretically distinct protein kinases could be detected by this method in lysates from NIH 3T3 cells. One of the kinases, a 42-kilodalton serine(threonine) kinase (PK42), was found to possess two- to fourfold-higher in vitro activity when isolated from serum-stimulated cells than when isolated from serum-starved cells. This kinase comigrated on sodium dodecyl sulfate-gels with a protein (p42) whose phosphotyrosine content increased in response to serum stimulation. The time courses of p42 tyrosine phosphorylation and PK42 activation were similar, reaching maximal levels within 10 min and returning to basal levels within 5 h. Both p42 tyrosine phosphorylation and PK42 activation were stimulated by low concentrations of phorbol esters, and the responses of p42 and PK42 to TPA were abolished by chronic 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment. Chronic TPA treatment had less effect on serum-induced p42 tyrosine phosphorylation and PK42 activation. PK42 and p42 bound to DEAE-cellulose, and both eluted at a salt concentration of 250 mM. Thus, PK42 and p42 comigrate and cochromatograph, and the kinase activity of PK42 correlates with the tyrosine phosphorylation of p42. These findings suggest that PK42 and p42 are related or identical, that PK42 is activated by tyrosine phosphorylation, and that this tyrosine phosphorylation can be regulated by protein kinase C.

1990 ◽  
Vol 10 (6) ◽  
pp. 3020-3026 ◽  
Author(s):  
J E Ferrell ◽  
G S Martin

We have surveyed fibroblast lysates for protein kinases that might be involved in mitogenesis. The assay we have used exploits the ability of blotted, sodium dodecyl sulfate-denatured proteins to regain enzymatic activity after guanidine treatment. About 20 electrophoretically distinct protein kinases could be detected by this method in lysates from NIH 3T3 cells. One of the kinases, a 42-kilodalton serine(threonine) kinase (PK42), was found to possess two- to fourfold-higher in vitro activity when isolated from serum-stimulated cells than when isolated from serum-starved cells. This kinase comigrated on sodium dodecyl sulfate-gels with a protein (p42) whose phosphotyrosine content increased in response to serum stimulation. The time courses of p42 tyrosine phosphorylation and PK42 activation were similar, reaching maximal levels within 10 min and returning to basal levels within 5 h. Both p42 tyrosine phosphorylation and PK42 activation were stimulated by low concentrations of phorbol esters, and the responses of p42 and PK42 to TPA were abolished by chronic 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment. Chronic TPA treatment had less effect on serum-induced p42 tyrosine phosphorylation and PK42 activation. PK42 and p42 bound to DEAE-cellulose, and both eluted at a salt concentration of 250 mM. Thus, PK42 and p42 comigrate and cochromatograph, and the kinase activity of PK42 correlates with the tyrosine phosphorylation of p42. These findings suggest that PK42 and p42 are related or identical, that PK42 is activated by tyrosine phosphorylation, and that this tyrosine phosphorylation can be regulated by protein kinase C.


2021 ◽  
Vol 15 (1) ◽  
pp. 54
Author(s):  
Jelena Milinković Budinčić ◽  
Lidija Petrović ◽  
Ljiljana Đekić ◽  
Milijana Aleksić ◽  
Jadranka Fraj ◽  
...  

Microencapsulation of bioactive substances is a common strategy for their protection and release rate control. The use of chitosan (Ch) is particularly promising due to its abundance, biocompatibility, and interaction with anionic surfactants to form complexes of different characteristics with relevance for use in microcapsule wall design. In this study, Ch/sodium dodecyl sulfate (SDS) microcapsules, without and with cross-linking agent (formaldehyde (FA) or glutaraldehyde (GA)), were obtained by the spray drying of vitamin E loaded oil-in-water emulsion. All of the microcapsules had good stability during the drying process. Depending on the composition, their product yield, moisture content, and encapsulation efficiency varied between 11–34%, 1.14–1.62%, and 94–126%, respectively. SEM and FTIR analysis results indicate that SDS as well as cross-linkers significantly affected the microcapsule wall properties. The profiles of in vitro vitamin E release from the investigated microcapsules fit with the Korsmeyer-Peppas model (r2 > 0.9). The chemical structure of the anionic surfactant was found to have a significant effect on the vitamin E release mechanism. Ch/SDS coacervates may build a microcapsule wall without toxic crosslinkers. This enabled the combined diffusion/swelling based release mechanism of the encapsulated lipophilic substance, which can be considered favorable for utilization in food and pharmaceutical products.


2002 ◽  
Vol 46 (7) ◽  
pp. 2292-2298 ◽  
Author(s):  
Fred C. Krebs ◽  
Shendra R. Miller ◽  
Bradley J. Catalone ◽  
Raina Fichorova ◽  
Deborah Anderson ◽  
...  

ABSTRACT In experiments to assess the in vitro impact of the candidate microbicides nonoxynol 9 (N-9), C31G, and sodium dodecyl sulfate (SDS) on human immune and epithelial cell viability, cell lines and primary cell populations of lymphocytic and monocytic origin were generally shown to be equally sensitive to exposures ranging from 10 min to 48 h. However, U-937 cells were more sensitive to N-9 and C31G after 48 h than were primary monocyte-derived macrophages. Cytokine activation of monocytes and lymphocytes had no effect on cell viability following exposure to these microbicidal compounds. Primary and passaged vaginal epithelial cultures and cell lines differed in sensitivity to N-9 and C31G but not SDS. These studies provide a foundation for in vitro experiments in which cell lines of human immune and epithelial origin can be used as suitable surrogates for primary cells to further investigate the effects of microbicides on cell metabolism, membrane composition, and integrity and the effects of cell type, proliferation, and differentiation on microbicide sensitivity.


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