Appearance Of New Proteins Research Articles

Regulation of abscisic acid metabolism in the aleurone layers of barley seeds

The regulation of metabolism of abscisic acid has been investigated in the isolated aleurone layers of barley (Hordeum vulgare L.) seeds. The rate of conversion of abscisic acid to phaseic acid is enhanced by two to five-fold when the tissue is pretreated with 10(-5) M of this hormone. This enhancement can be observed with a pretreatment as short as two hours, and is prevented by transcription and translation inhibitors. The enhancement is accompanied by the appearance of new proteins which are induced by abscisic acid. It is suggested that some of these ABA induced proteins are probably involved in the conversion from abscisic acid to phaseic acid.

Effect of experimental diabetes on the susceptibility of myelin proteins to proteolysis.

To investigate abnormalities in peripheral nerve myelin in experimental diabetes, we studied the effects of the proteolytic enzymes trypsin and alpha-chymotrypsin on the proteins of this membrane, obtained from the sciatic nerves of normal rats and from animals made diabetic with streptozotocin. The dominant effect of the proteolytic enzymes was to incompletely degrade the major membrane protein (mol. wt. 28,000), with the appearance of new protein (mol. wt. 20,000). Using myelin isolated from the nerves of diabetic animals, the reaction was approximately one-half that of the controls (P less than 0.01) for both enzymes. When, however, the myelin protein affected by trypsin and chymotrypsin was isolated from the membrane and then incubated with the proteolytic enzyme, its proteolysis was complete and took place at the same rate in the diabetic animals and controls. These findings suggest that, in this model of experimental diabetes, there is an alteration in the structure of peripheral nerve myelin that inhibits interaction between the protein in the membrane bilayer and two water soluble proteolytic enzymes. This alteration could not be demonstrated in protein isolated from the membrane, suggesting that the change relates to the interaction of the protein and other components of myelin, rather than to chemical alteration in the protein per se.

Chromosomal proteins in hepatocarcinogenesis.

The chromosomal proteins of rat liver were studied by SDS-gel electrophoresis during the process of nitrosomorpholine-induced hepatocarcinogenesis, in the primary hepatomas thus obtained, and in their metastases. It was found that an increased proteolytic activity was present in liver homogenates from carcinogen-fed animals which caused differences between the nonhistone chromosomal proteins of control and carcinogen-treated livers. These differences disappeared in the presence of the protease inhibitor PMSF. In the primary hepatomas slight quantative changes were observed: an increased amount of two proteins of 43000 and 63000 daltons molecular weight, respectively, and a decrease in the histone subfraction H 1 degrees. In the metastases both quantative and qualitative differences were detected: a strong decrease in the protein bands corresponding to the contractile proteins alpha-tubulin, beta-tubulin, and actin; an increased content of the 63000 dalton protein; the appearance of new proteins of approximately 60000, 90000, and 120000 daltons molecular weight, and the complete disappearance of histone H 1 degrees.

The Mechanism of Steroid-Hormone Regulation of Transcription of Specific Eukaryotic Genes

This chapter discusses that growth and differentiation is a complex process that requires an integrated synthesis of DNA along with transcription of a full complement of RNA and expression of protein for each new cell type. Differentiation can refer either to morphological changes or to the appearance of a new biochemical function. In a variety of eukaryotic model systems, tissue growth and differentiation can be induced with specific chemical effectors. Initiation of active metabolism in cell division of these tissues allows a precise temporal analysis of the biochemical events that result in the differentiation response. Thus, these responses are specific for either embryonic or immature tissues. The effect of glucocorticoids on the differentiation of chick embryo retinal cells provides one example of hormone-dependent biochemical differentiation. The decidual cell reaction in the uterus in response to progesterone is manifested by proliferation of cells similar to that occurring on implantation of a blastocyst. It also reviews that steroid hormones are capable of stimulating prematurely the appearance of new proteins and target cell functions under well defined conditions. Moreover, these events are a primary part of the normal adult response during maturation and presumably are under the direction of the endogenous hormones.

魚類の生殖腺成熟に関する生理学的研究-I

Differences by sex in the composition of plasma protein, its hormonal control and relation-ship between plasma protein and yolk protein of Ayu, Plecoglossus altivelis, were studied elec-trophoretically and immunologically. In immunoelectrophoresis, two new proteins (Fm-a and Fm-b) appeared in the female plasma with the commencement of vitellogenesis. Fm-a was composed of two fractions (fractions 9 and 11) in starch-gel electrophoresis, which increased in the maturing female plasma. In males, the appearance of new protein was not observed. Estradiol-17β and estradiol-benzoate induced the dose-dependent synthesis of the new specific proteins in male fish, but testosterone, testosterone-propionate, hydrocortisone acetate and progesterone failed to produce the specific proteins. Ovarian extract caused three precipitin bands (Eg-a, Eg-b and Eg-c) in response to anti-maturing female Ayu plasma. Fm-a and Eg-a (a dominant fraction of ovarian extract) had the same antigenic component and binding sub-stances such as calcium, lipid and polysaccharide. Eg-a was also composed of two fractions in starch-gel electr ophoresis. In maturing females, plasma calcium increased simultaneously with the appearance of new specific protein and in estrogen-treated males (dose-dependent). These results suggest that in maturing female Ayu, new specific proteins, formed outside the ovary with the stimulation of estrogen, appear in the female plasma and then are taken up by the oocyte with the commencement of vitellogenesis.