Sec63p and Kar2p are required for the translocation of SRP-dependent precursors into the yeast endoplasmic reticulum in vivo.
The translocation of secretory polypeptides into the endoplasmic reticulum (ER) occurs at the translocon, a pore-forming structure that orchestrates the transport and maturation of polypeptides at the ER membrane. In yeast, targeting of secretory precursors to the translocon can occur by two distinct pathways that are distinguished by their dependence upon the signal recognition particle (SRP). The SRP-dependent pathway requires SRP and its membrane-bound receptor, whereas the SRP-independent pathway requires a separate receptor complex consisting of Sec62p, Sec63p, Sec71p, Sec72p plus lumenal Kar2p/BiP. Here we demonstrate that Sec63p and Kar2p are also required for the SRP-dependent targeting pathway in vivo. Furthermore, we demonstrate multiple roles for Sec63p, at least one of which is exclusive to the SRP-independent pathway.
School of Biological Sciences, 2.205 Stopford Building, University of Manchester, Oxford Road, Manchester M13 9PT, UK.
B P
BP
Young
R A
RA
Craven
P J
PJ
Reid
M
M
Willer
C J
CJ
Stirling
D002462:Cell Membrane / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005020:Ethyl Methanesulfonate / Q000494:pharmacology; D005656:Fungal Proteins / Q000378:metabolism*; D005838:Genotype; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins; D008715:Methionine / Q000378:metabolism; D016296:Mutagenesis; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D018271:Signal Recognition Particle / Q000378:metabolism*
D005656:Fungal Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C060153:KAR2 protein, yeast; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C074215:SEC63 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D018271:Signal Recognition Particle; D005020:Ethyl Methanesulfonate; D008715:Methionine