Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

Elongation Arrest Is Not a Prerequisite for Secretory Protein Translocation across the Microsomal Membrane

Vivian Siegel and Peter Walter
The Journal of Cell Biology
Vol. 100, No. 6 (Jun., 1985), pp. 1913-1921
Stable URL: http://www.jstor.org/stable/1611309
Page Count: 9
  • More info
  • Cite this Item
Elongation Arrest Is Not a Prerequisite for Secretory Protein Translocation across the Microsomal Membrane
Preview not available

Abstract

Signal recognition particle (SRP) is a ribonucleoprotein consisting of six distinct polypeptides and one molecule of small cytoplasmic 7SL RNA. It was previously shown to promote the co-translational translocation of secretory proteins across the endoplasmic reticulum by (a) arresting the elongation of the presecretory nascent chain at a specific point, and (b) interacting with the SRP receptor, an integral membrane protein of the endoplasmic reticulum which is active in releasing the elongation arrest. Recently a procedure was designed by which the particle could be disassembled into its protein and RNA components. We have further separated the SRP proteins into four homogeneous fractions. When recombined with each other and with 7SL RNA, they formed fully active SRP. Particles missing specific proteins were assembled in the hope that some of these would retain some functional activity. SRP(-9/14), the particle lacking the 9-kD and 14-kD polypeptides, was fully active in promoting translocation, but was completely inactive in elongation arrest. This implied that elongation arrest is not a prerequisite for protein translocation. SRP receptor was required for SRP(-9/14)-mediated translocation to occur, and thus must play some role in the translocation process in addition to releasing the elongation arrest.

Page Thumbnails

  • Thumbnail: Page 
1913
    1913
  • Thumbnail: Page 
1914
    1914
  • Thumbnail: Page 
1915
    1915
  • Thumbnail: Page 
1916
    1916
  • Thumbnail: Page 
1917
    1917
  • Thumbnail: Page 
1918
    1918
  • Thumbnail: Page 
1919
    1919
  • Thumbnail: Page 
1920
    1920
  • Thumbnail: Page 
1921
    1921