Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published May 1982 | Published
Journal Article Open

Signal recognition protein is required for the integration of acetylcholine receptor delta subunit, a transmembrane glycoprotein, into the endoplasmic reticulum membrane


Purified Signal Recognition Protein (SRP) has previously been shown to be required for the translocation of secretory proteins across the microsomal membrane (Walter and Blobel, 1980. Proc. Natl. Acad. Sci. U. S. A. 77:7, 112-7, 116) and to function in the early events of this process (Walter and Blobel, 1981. J. Cell Biol. 91:557-561). We demonstrate here that the delta subunit of acetylcholine receptor (AChR- delta), a transmembrane glycoprotein, likewise requires SRP for its asymmetric integration into microsomal membranes. We further demonstrate by partial sequence analysis that AChR-delta is synthesized with a transient NH2-terminal signal sequence of 21 residues that is cleaved off during integration into microsomal membranes. Integration of AChR-delta into the microsomal membrane vesicles proceeded asymmetrically, yielding a large (44 kdalton) core-glycosylated domain, inaccessible to externally added proteolytic enzymes and a smaller (approximately 16 kdalton) domain exposed on the outside of the vesicles and accessible to externally added proteolytic enzymes. The NH2 terminus of the molecule is contained in the 44-kdalton domain.

Additional Information

© 1982 by The Rockefeller University Press Received for publication 22 December 1981, and in revised form 26 January 1982. We are grateful to Drs. Bruce A. Cunningham and John Hemperly for performing the run shown in Fig. 3b on their Beckman sequencer, and for helpful discussions. We thank Ms. Beth Weiner for skillful assistance with the sequencing. This work was supported by a grant from the Muscular Dystrophy Foundation. D.J. Anderson is a National Science Foundation predoctoral fellow.

Attached Files

Published - ANDjcb82.pdf


Files (597.4 kB)
Name Size Download all
597.4 kB Preview Download

Additional details

August 22, 2023
October 16, 2023