The beta-subunit of the signal recognition particle receptor is a novel GTP-binding protein without intrinsic GTPase activity

The Journal of Biological Chemistry
K R Legate, D W Andrews

Abstract

The beta-subunit of the signal recognition particle receptor (SRbeta), a member of the Ras family of small molecular weight GTPases, is involved in the targeting of nascent polypeptide chains to the protein translocation machinery in the endoplasmic reticulum membrane. We purified SRbeta from an expressing strain of Escherichia coli and investigated the properties of the isolated GTPase. We find that, unlike other Ras family GTPases, most SRbeta purifies bound to GTP, and SRbeta-bound GTP is not easily exchanged with solution GTP. SRbeta possesses no detectable GTPase activity. Although a stable interaction between SRbeta and ribosomes is observed, SRbeta is not stimulated to hydrolyze GTP when incubated with ribosomes or ribosome-nascent chains. A GTPase mutant harboring a mutation in a region predicted to be functionally important, based on observations made in related GTPases, binds GTP with faster kinetics and appears to be a less stable protein but otherwise displays similar properties to the wild-type SRbeta GTPase. Our results demonstrate that as an isolated GTPase, SRbeta functions differently from the Arf- and Ras-type GTPases that it is most closely related to by sequence.

References

Nov 1, 1986·Proceedings of the National Academy of Sciences of the United States of America·U C KriegA E Johnson
Apr 1, 1987·Proceedings of the National Academy of Sciences of the United States of America·T E DeverW C Merrick
Jan 1, 1987·Annual Review of Biochemistry·M Barbacid
Nov 1, 1984·Nature·P H SeeburgA D Levinson
Jan 6, 1995·The Journal of Biological Chemistry·R A KahnM Cavenagh
Jan 1, 1996·Annual Review of Biochemistry·F L Zhang, P J Casey
Apr 18, 2001·Methods in Enzymology·S Koyama, A Kikuchi
Apr 18, 2001·Methods in Enzymology·Y Wang, J Colicelli
Jun 1, 2001·Methods : a Companion to Methods in Enzymology·A BellelliM T Wilson
Nov 22, 2001·Biochemistry and Cell Biology = Biochimie Et Biologie Cellulaire·K R Legate, D W Andrews

❮ Previous
Next ❯

Citations

Aug 12, 2009·Journal of Experimental & Clinical Cancer Research : CR·Yaqing ZhangWei Yan
Apr 22, 2006·Proceedings of the National Academy of Sciences of the United States of America·Thomas U SchwartzGünter Blobel
Nov 10, 2004·Proceedings of the National Academy of Sciences of the United States of America·Andrej I IvanovMarshall Nirenberg
Sep 21, 2019·The Journal of Cell Biology·Yu-Hsien Hwang FuShu-Ou Shan
Aug 14, 2019·Biological Chemistry·Klemens WildIrmgard Sinning
Jul 3, 2021·International Journal of Molecular Sciences·Morgana K KelloggAndrey L Karamyshev

❮ Previous
Next ❯

Related Concepts

Related Feeds

ASBMB Publications

The American Society for Biochemistry and Molecular Biology (ASBMB) includes the Journal of Biological Chemistry, Molecular & Cellular Proteomics, and the Journal of Lipid Research. Discover the latest research from ASBMB here.