These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Induction of tyrosine aminotransferase and amino acid transport in rat hepatoma cells by insulin and the insulin-like growth factor, multiplication-stimulating activity. Mediation by insulin and multiplication-stimulating activity receptors.
    Author: Heaton JH, Schilling EE, Gelehrter TD, Rechler MM, Spencer CJ, Nissley SP.
    Journal: Biochim Biophys Acta; 1980 Oct 01; 632(2):192-203. PubMed ID: 6106509.
    Abstract:
    Insulin stimulates a 2-fold increase in the amount of tyrosine aminotransferase and a 5-10-fold increase in the rate of amino acid transport in dexamethasone-treated rat hepatoma cells. In order to determine whether these effects are mediated by insulin receptors or receptors for insulin-like growth factors, we have examined the binding of 125I-labeled insulin and 125I-labeled multiplication-stimulating activity, a prototype insulin-like growth factor, and compared the biological effects of these polypeptides. Insulin and multiplication-stimulating activity cause an identical increase in transaminase activity and transport velocity; half-maximal biological effects were observed at 35 ng/mg (5.5 nM) insulin and 140 ng/ml multiplication-stimulating activity. The hepatoma cells display typical insulin receptors of appropriate specificity; half-maximal displacement of tracer insulin binding occurred at 33 ng/ml unlabeled insulin, but only at 2500 ng/ml unlabeled multiplication-stimulating activity. Specific multiplication-stimulating activity receptors also were demonstrated with which insulin did not interact even at 10 micrograms/ml. Half-maximal displacement of tracer multiplication-stimulating activity occurred at 200 ng/ml unlabeled multiplication-stimulating activity. We conclude that insulin cannot act via the multiplication-stimulating activity receptor and presumably acts via typical insulin receptors. The effects of multiplication-stimulating activity on enzyme induction and amino acid transport are probably mediated primarily via the multiplication-stimulating activity receptor.
    [Abstract] [Full Text] [Related] [New Search]