The phosphorylation of eukaryotic ribosomal proteins

McGarvey, Michael J (1981) The phosphorylation of eukaryotic ribosomal proteins. PhD thesis, University of Glasgow.

Abstract

Two different casein kinase (CKI and CKII) and one histone kinase (HK) activities were resolved from the ribosome-free cytoplasm of Krebs II ascites cells by chromatography on DEAE-cellulose and phosphocellulose. One of these, CKII was able to use either ATP or GTP to phosphorylate the acidic 6 OS subunit protein L, but phosphorylated no other ribosomal proteins, A second casein kinase, CKI could use ATP but not GTP, to phosphorylate . CKI was less specific than CKII and apart from was able to phosphorylate a number of proteins which were phosphorylated in vivo (S6, Sa and Sb) as well as a protein which was not phosphorylated vivo (S7). The other kinase, HK was able to use ATP to phosphorylate S6 as well as other proteins (S7, S1O, S14, S20 and L35) which were not phosphorylated vivo. None of these three protein kinases was stimulated by cyclic AMP or inhibited by the heat stable cyclic AMP-dependent protein kinase inhibitor protein. CKI and CKII were both inhibited, to different extents, by heparin whereas HK activity was stimulated by the presence of heparin. Neither CKI nor CKII was affected by the presence of calmodulin but HK was stimulated four-fold. CKII, but not CKI or HK, was selectively inhibited by protein kinase inhibitor protein 'CKGI' (Job et al. 1979). Krebs II ascites ribosomal proteins S3, S2 and L14 (which became phosphorylated when ascites cell incubation medium contained glucose and amino acids) were not phosphorylated by any of these three protein kinases. Ascites cells incubated in medium containing glucose and amino acids however contained a labile protein kinase activity not seen previously. Protein kinases from both Krebs II ascites cells and other tissues phosphorylated proteins of similar molecular weight to S6 and L in a preparation of extracted ribosomal protein. Protein kinases from the cytosol of BHK cells were resolved on DEAE-cellulose. In cytosol from cells infected by pseudorabies virus a novel histone kinase activity was detected. Analysis on one-dimensional SDS gel electrophoresis showed that an as yet unidentified protein of the 4OS subunit of molecular weight 22,000 was specifically phosphorylated by this new protein kinase activity.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: David Leader
• Keywords: Biochemistry
• Date of Award: 1981
• Depositing User: Enlighten Team
• Unique ID: glathesis:1981-73202
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 14 Jun 2019 08:56
• Last Modified: 14 Jun 2019 08:56
• URI: https://theses.gla.ac.uk/id/eprint/73202