UMMS Affiliation

Department of Biochemistry and Molecular Biology

Date

8-1-1991

Document Type

Article

Subjects

Animals; Chromatography, Gel; Cross-Linking Reagents; Dogs; Electrophoresis, Polyacrylamide Gel; Endoplasmic Reticulum; Immunoblotting; Intracellular Membranes; Kinetics; Liposomes; Membrane Proteins; Microsomes; Pancreas; Protein Binding; Ribosomes; Succinimides

Disciplines

Cell Biology | Immunopathology | Life Sciences | Medicine and Health Sciences

Abstract

We have used the membrane-impermeable, thiol-cleavable, crosslinker 3,3'-dithio bis (sulfosuccinimidylpropionate) to identify proteins that are in the vicinity of membrane-bound ribosomes of the RER. A specific subset of RER proteins was reproducibly crosslinked to the ribosome. Immunoblot analysis of the crosslinked products with antibodies raised against signal recognition particle receptor, ribophorin I, and the 35-kD subunit of the signal sequence receptor demonstrated that these translocation components had been crosslinked to the ribosome, but each to a different extent. The most prominent polypeptide among the crosslinked products was a 180-kD protein that has recently been proposed to be a ribosome receptor (Savitz, A.J., and D.I. Meyer, 1990. Nature (Lond.). 346: 540-544). RER membrane proteins were reconstituted into liposomes and assayed with radiolabeled ribosomes to determine whether ribosome binding activity could be ascribed to the 180-kD protein. Differential detergent extraction was used to prepare soluble extracts of microsomal membrane vesicles that either contained or lacked the 180-kD protein. Liposomes reconstituted from both extracts bound ribosomes with essentially identical affinity. Additional fractionation experiments demonstrated that the bulk of the ribosome binding activity present in detergent extracts of microsomal membranes could be readily resolved from the 180-kD protein by size exclusion chromatography. Taken together, we conclude that the 180-kD protein is in the vicinity of membrane bound ribosomes, yet does not correspond to the ribosome receptor.

Rights and Permissions

Citation: J Cell Biol. 1991 Aug;114(4):639-49.

Related Resources

Link to Article in PubMed

PubMed ID

1869584

 
 

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