Protein transport into canine pancreatic microsomes: a quantitative approach.
Transport of presecretory proteins into the mammalian rough endoplasmic reticulum involves a protein translocase that comprises the integral membrane proteins Sec61alphap, Sec61betap, and Sec61gammap as core components. Electron microscopic analysis of protein translocase in rough microsomal membranes suggested that between three and four heterotrimeric Sec61p complexes form the central unit of protein translocase. Here we analyzed the stoichiometry of heterotrimeric Sec61p complexes present in cotranslationally active protein translocases of canine pancreatic microsomes and various other lumenal and membrane components believed to be subunits of protein translocase and to be involved in covalent modifications. Based on these numbers, the capacity for cotranslational transport was estimated for the endoplasmic reticulum of the human pancreas.
Guth
Silvia
S
Medizinische Biochemie und Molekularbiologie, Universität des Saarlandes, Homburg, Germany. bcrzim@med-rz.uni-saarland.de
Völzing
Christian
C
Müller
Anika
A
Jung
Martin
M
Zimmermann
Richard
R
D000818:Animals; D002474:Cell-Free System; D004285:Dogs; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism*; D010179:Pancreas / Q000166:cytology* / Q000378:metabolism*; D021381:Protein Transport; D000069816:SEC Translocation Channels
D008565:Membrane Proteins; D000069816:SEC Translocation Channels