Structure and function of the stalk, a putative regulatory element of the yeast ribosome. Role of stalk protein phosphorylation |
| |
Authors: | M A Rodriguez-Gabriel G Bou E Briones R Zambrano M Remacha J P G Ballesta |
| |
Institution: | (1) Centro de Biología Molecular, CSIC and UAM, Canto Blanco, 28049 Madrid, Spain |
| |
Abstract: | The ribosomal stalk is involved directly in the interaction of the elongation factors with the ribosome during protein synthesis.
The stalk is formed by a complex of five proteins, four small acidic polypepties and a larger protein which directly interacts
with the rRNA at the GTPase center. In eukaryotes, the acidic components correspond to the 12 kDa P1 and P2 proteins, and
the RNA binding component is protein P0. All these proteins are found to be phosphorylated in eukaryotic organisms. Previousin vitro data suggested this modification was involved in the activity of this structure. To confirm this possibility a mutational
study has shown that phosphorylation takes place at a serine residue close to the carboxyl end of proteins P1, P2 and P0.
This serine is part of a consensus casein kinase II phosphorylation site. However, by using a yeast strain carrying a temperature
sensitive mutant, it has been shown that CKII is probably not the only enzyme responsible for this modification. Three new
protein kinases, RAPI, RAPII and RAPIII, have been purified and compared with CKII and PK60, a previously reported enzyme
that phosphorylates the stalk proteins. Differences among the five enzymes have been studied. It has also been found that
some typical effects of the PKC kinase stimulate thein vitro phosphorylation of the stalk proteins. All the data available suggest that phosphorylation, although it is not involved in
the interaction of the acidic proteins with the ribosome, affects ribosome activity and might participate in some ribosome
regulatory mechanism.
Presented at theSymposium on Regulation of Translation of Genetic Information by Protein Phosphorylation, 21st Congress of the Czechoslovak
Society for Microbiology, Hradec Králové (Czech Republic), September 6–10, 1998. |
| |
Keywords: | |
本文献已被 PubMed SpringerLink 等数据库收录! |
|