[HTML][HTML] Sec63p and Kar2p are required for the translocation of SRP‐dependent precursors into the yeast endoplasmic reticulum in vivo

BP Young, RA Craven, PJ Reid, M Willer… - The EMBO …, 2001 - embopress.org
BP Young, RA Craven, PJ Reid, M Willer, CJ Stirling
The EMBO journal, 2001embopress.org
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 …
Abstract
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.
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