Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.
Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
Regulation of an eukaryotic initiation factor-2 associated 67 kDa glycoprotein ( p67) during heat shock in animal cells
Abstract
Eukaryotic initiation factor-2 (eIF-2) associated polypeptide (p$\sp{67}$) plays an important role in the regulation of protein synthesis initiation in the mammalian cells. Under certain physiological conditions, phosphorylation of the $\alpha$-subunit of eIF-2 by kinases leads to eIF-2 inactivation and thereby protein synthesis inhibition. p$\sp{67}$ can protect the eIF-2$\alpha$ from inhibitory phosphorylation and therefore promotes protein synthesis even in the presence of eIF-2 kinases. p$\sp{67}$ level in the cells is regulated by two different mechanisms, (i) by the activation of a p$\sp{67}$-deglycosylase. Heme-deficient reticulocyte and vaccinia viral infected animal cells use this mechanism. A p$\sp{67}$-deglycosylase has been purified from heme deficient reticulocyte lysate. (ii) at the mRNA level. This mechanism is used in serum starvation and heat shock. Regulation of p$\sp{67}$ at the transcriptional level in response to heat shock was studied in rat hepatoma (KRC-7) cells. Cloning and sequence analysis of the 5$\sp\prime$ upstream region of p$\sp{67}$ genomic DNA revealed the presence of heat shock regulatory element. Transcriptional regulation of p$\sp{67}$ in response to heat shock was studied by deleting HSE from p$\sp{67}$ promoter. Deletion of HSE caused significant decrease in the promoter activity upon heat shock treatment. Heat shock resulted in a time dependent prolonged elevation upon heat shock treatment. Heat shock resulted in a time dependent prolonged elevation in the level of p$\sp{67}$ mRNA, which was accompanied by increased translation of p$\sp{67}$ protein. It was observed that a p$\sp{67}$-deglycosylase was activated during 15 min of heat shock and p$\sp{67}$ mostly existed in deglycosylated form during this phase. Loss of glycosyl residues obliterated p$\sp{67}$ activity and it no longer protected eIF-2$\alpha$ from inhibitory phosphorylation. However the level of eIF-2$\alpha$ phosphorylation decreased after 30 min of heat shock. During this second phase, newly synthesized p$\sp{67}$ protein was observed and was found to be glycosylated. Decrease in the level of eIF-2$\alpha$ phosphorylation was paralleled by an induction of p$\sp{67}$ in the glycosylated form.
Subject Area
Biochemistry|Molecular biology
Recommended Citation
Chatterjee, Madhumita, "Regulation of an eukaryotic initiation factor-2 associated 67 kDa glycoprotein ( p67) during heat shock in animal cells" (1997). ETD collection for University of Nebraska-Lincoln. AAI9736925.
https://digitalcommons.unl.edu/dissertations/AAI9736925