Molecular sorting of proteins into the cisternal secretory pathway.
Cotranslational translocation of exportable proteins across the RER membrane prior to their release into the extracellular space has been essentially described by use of canine pancreatic microsomal membranes. Intracisternal segregation of nascent secretory proteins was observed to be irreversible and proteolytic removal of signal sequences resulted in conformationally mature and stable proteins. Structural studies on various translocation peptides from both eukaryotic and prokaryotic preparations showed that many of them have a comparable three-domain organization. A hydrophilic amino-terminal domain is followed by a core region of hydrophobic amino acids and by the region in which the proteolytic cleavage occurs. Membrane components involved in the translocation process namely the signal recognition particle and the SRP receptor as well as the way the vectorial transport mechanism of nascent secretory proteins occurs are also discussed.
Scheele
G A
GA
Laboratory of Cell and Molecular Biology, Rockefeller University, New York, NY 10021.
D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D004285:Dogs; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006868:Hydrolysis; D008565:Membrane Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D010179:Pancreas / Q000378:metabolism; D014176:Protein Biosynthesis; D011506:Proteins / Q000378:metabolism*
D008565:Membrane Proteins; D011506:Proteins