[Actin isoforms--functional differentiation, changes in cell pathology].
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Actins↗
Biomedical subjects
M Malicka-Błaszkiewicz
Publications and source records attributed to M Malicka-Błaszkiewicz.
Identification of actin from hepatoma Morris 5123 cells.
The hepatoma Morris 5123 tumor growth is accompanied by changes in actin content and polymerization (Malicka-Błaszkiewicz et al. (1995) Mat. Med. Pol., 27, 115-118; Nowak et al. (1995) J. Exp. Cancer Res. 14, 37-40). Presently actin isoforms from cytosol and cytoskeleton fractions were separated by SDS/PAGE and identified with antibodies directed against different actin isoforms. Actin isolated from the cytosol by affinity chromatography on DNase I bound to agarose shows the presence of only one protein spot on 2D gel electrophoresis corresponding to the mobility of the rabbit a skeletal muscle actin (Mr 43,000) and isoelectric point equal to 5.3. It interacts only with monoclonal anti beta actin isoform antibodies, posing the question of differential affinity of actin isoforms to DNase I.
Actins↗
DNase I-like activity and actin content in the liver of some vertebrates.
Total actin content and F:G actin ratio were determined in the liver cytosol of fish, frogs and mouse by measurements of inhibition of exogenous crystalline bovine pancreatic DNase I. Endogenous DNase I-like activity, was found in all examined livers after electrophoresis in the presence of sodium dodecyl sulfate and subsequent enzyme renaturation. It is concluded that DNase I-like enzymes occur in the liver cytosol in a latent form, probably bound to cytoplasmic actin.
Actins↗
Partial purification and some properties of a liver alkaline ribonuclease from the frog Rana esculenta.
1. RNAases varying in pH optimum, activation with pCMB, sensitivity towards temperature and acid treatment, as well as electrophoretic mobility were found in Rana esculenta liver extract. 2. Of the three activity peaks of alkaline ribonuclease separated on CM-cellulose with 2000-fold purification, RNAase of peak C is thermo- and acid-stable and exhibits specificity for pyrimidine bases, preferring poly(U) over poly(C). 3. Differences in the specific "inhibitory effect" of frog liver supernatant on the frog liver alkaline RNAase were observed.
Animals↗
Acid phosphatase from liver of the frog Rana esculenta, separation and partial characterization of multiple forms.
1. Acid phosphatase (AcPase) from liver of the frog, Rana esculenta has been isolated and purified. The enzyme is heterogeneous, showing 4 activity zones on disc electrophoresis. The AcPase was separated into 3 peaks on DEAE-cellulose. Peak A corresponding to the electrophoretic AcPase IV represents an extensively purified enzyme form. 2. The separated enzyme forms are change isomers with a molecular weight of about 33,000. They differ markedly in substrate requirements and sensitivity towards activators and inhibitors. All of them are highly activated by dithiothreitol, show a rather restricted substrate specificity, and marked activity against ATP.
Acid Phosphatase↗
Rat liver DNase I-like activity and its interaction with actin.
Monomeric G actin, total actin and the F:G actin ratio were determined in the rat liver cytosol and nucleoplasm by measuring the inhibition of standard crystalline DNase I. Actin was purified from rat liver nucleoplasm by Sephadex filtration. Accompanying the considerable amount of actin an endogenous DNase I like activity was found in rat liver cytosol and nucleoplasm. It was shown, that similarly to DNase I from bovine pancreas the liver DNase was inhibited by mammalian and avian skeletal muscle actin as well as by endogenous liver actin, as verified by electrophoresis of DNase containing extracts on polyacrylamide gels with incorporated DNA.
Actins↗
The RNAse-RNAse inhibitor system in the liver of the frog Rana esculenta: subcellular distribution and differential binding of inhibitor with multiple RNAses.
The aim of our work was to investigate the biological basis of the existence of multiple alkaline RNAses in the Rana esculenta liver with respect to formation of a RNAse-RNAse inhibitor complex (latent RNAse). Subcellular distribution indicated that most of the alkaline RNAse activity appeared in the high-speed supernatant and mainly in a latent form bound to an endogenous inhibitor. This RNAse-RNAse inhibitor complex was isolated, the bound RNAse activity was released and found to correspond to RNAse III and RNAse IV, the two most cathodic RNAses present in the supernatant fraction. The two RNAses differed markedly in the ability to interact with the inhibitor and this might be essential for the different biological roles the RNAses may play in the regulation of cytoplasmic RNA level. On the basis of molecular weight determinations we assume that the enzyme-inhibitor complex is shared by two different RNAses.
Animals↗
Actin content and polymerization in tumour, liver and serum of the hepatoma Morris 5123 tumour bearing rats.
Monomeric G-actin, total actin and filamentous F-actin were examined during the growth of experimental tumour hepatoma Morris 5123. Actin was measured by the inhibition of the standard DNase I from bovine pancreas. A remarkable increase in total actin, and F-actin content, as well as in the state of actin polymerization (measured by the F:G actin ratio) was shown in the cytosol of the tumour cells in the second week of the tumour growth, followed by a rapid decrease in the third week. Parallel observations were made in the cytosol of the liver and in the serum of the tumour bearing rats. The results were compared with the data obtained for control healthy rats. It was shown that hepatoma Morris tumour growth is accompanied by the changes in the actin content and polymerization, occurring also in the liver of the host animal. Only G-actin was found in the serum. It increased significantly in the second week of tumour growth as compared with the G-actin level in the serum of the control healthy rats.
Actins↗