摘要:

AbstractFollowing a single injection of hydrocortisone into adrenalectomized rats, the levels of tryptophan pyrrolase and tyrosine transaminase in the liver first rise and then decrease to their basal levels. Although actinomycin D blocks the initial steroid‐induced increase, later administration of the antibiotic (or of 5‐fluorouracil) causes an increase in the levels of these enzymes. A mechanism is proposed to account for the late response to inhibitors of RNA synthesis in which a “cytoplasmic repressor” can inhibit the translation of the messenger RNA's corresponding to tryptophan pyrrolase and tyrosine transaminase. Cytoplasmic repression is postulated to depend on continued RNA and protein synthesis, and the “repressor” is thought to have a rapid rate

ISSN:0095-9898    

DOI:10.1002/jcp.1030660413

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1965

数据来源: WILEY

摘要:

AbstractThe case for believing that growth hormone exerts its protein anabolic action by stimulating messenger RNA synthesis is summarized. Ribosomes, but not polysomes, from liver of rats have amino acid incorporating abilitiesin vitrowhich are directly related to the level of circulating growth hormone in the rat. Growth hormone treatment of rats stimulates labeling of all types of RNA including mRNA, possibly by activating the liver RNA polymerase. Growth hormone can exert some of its stimulating activity even in actinomycin‐treated rats. It is argued that control of rate, as opposed to type, of protein synthesized would be more likely to be exercised at the cytoplasmic rather than the genetic level, and anomalous results are examined in light of this suggestio

ISSN:0095-9898    

DOI:10.1002/jcp.1030660414

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1965

数据来源: WILEY

摘要:

AbstractIn considering the mechanisms controlling the expression of genetic information in mammalian cells, one is faced with the consideration that the multi‐cellular organism exists in two environments. The external environment requires controls for the maintenance of nutrition and respiration. The internal environment must be maintained constant for the survival of the organism as a whole. The liver is in a unique position, with its cells subject to pressures from both internal and external environment. Several mechanisms of enzyme regulation in which one enzyme demonstrates both controls are discussed. Elimination of the portal system, the liver's direct contact with the external environment, does not alter the basic control mechanisms. However, neoplastic transformation of hepatic cells radically alters both internal and external controls. Most external controls are lost, and those that remain are in part dependent on internal control mechanisms. On the basis of previous findings, the membrane of the endoplasmic reticulum is suggested as being the site of action of the steroid hormone

ISSN:0095-9898    

DOI:10.1002/jcp.1030660415

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1965

数据来源: WILEY

ISSN:0095-9898    

DOI:10.1002/jcp.1030660416

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1965

数据来源: WILEY

ISSN:0095-9898    

DOI:10.1002/jcp.1030660402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1965

数据来源: WILEY