The signal sequence of the p62 protein of Semliki Forest virus is involved in initiation but not in completing chain translocation.
So far it has been demonstrated that the signal sequence of proteins which are made at the ER functions both at the level of protein targeting to the ER and in initiation of chain translocation across the ER membrane. However, its possible role in completing the process of chain transfer (see Singer, S. J., P. A. Maher, and M. P. Yaffe. Proc. Natl. Acad. Sci. USA. 1987. 84:1015-1019) has remained elusive. In this work we show that the p62 protein of Semliki Forest virus contains an uncleaved signal sequence at its NH2-terminus and that this becomes glycosylated early during synthesis and translocation of the p62 polypeptide. As the glycosylation of the signal sequence most likely occurs after its release from the ER membrane our results suggest that this region has no role in completing the transfer process.
Garoff
H
H
Department of Molecular Biology, Karolinska Institute, Huddinge, Sweden.
Huylebroeck
D
D
Robinson
A
A
Tillman
U
U
Liljeström
P
P
D000595:Amino Acid Sequence; D000818:Animals; D001216:Asparagine; D001483:Base Sequence; D001692:Biological Transport / Q000502:physiology; D002474:Cell-Free System; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006031:Glycosylation; D008969:Molecular Sequence Data; D010442:Peptide Chain Initiation, Translational / Q000502:physiology; D014176:Protein Biosynthesis / Q000502:physiology; D021382:Protein Sorting Signals / Q000502:physiology*; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D012672:Semliki forest virus / Q000378:metabolism*; D013997:Time Factors; D014764:Viral Proteins / Q000378:metabolism*
D021382:Protein Sorting Signals; D014764:Viral Proteins; D001216:Asparagine