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- Title
Endoplasmic Reticulum Exit of a Secretory Glycoprotein in the Absence of Sec24p Family Proteins in Yeast.
- Authors
Karhinen, Leena; Bastos, Ricardo Nunes; Jokitalo, Eija; Makarow, Marja
- Abstract
Glycoproteins exit the endoplasmic reticulum (ER) of the yeastSaccharomyces cerevisiaein coàt protein complex II (COPII) coated vesicles. The coat consists of the essential proteins Sec23p, Sec24p, Sec13p, Sec31p, Sar1p and Sec16p. Sec24p and its two nonessential homologues Sfb2p and Sfb3p have been suggested to serve in cargo selection. Using temperature-sensitivesec24-1mutants, we showed previously that a secretory glycoprotein, Hsp150, does not require functional Sec24p for ER exit. Deletion ofSFB2,SFB3or both from wild type or the deletion ofSFB2fromsec24-1cells did not affect Hsp150 transport.SFB3deletion has been reported to be lethal insec24-1. However, here we constructed asec24-1Δ sfb3and asec24-1Δ sfb2Δ sfb3strain and show that Hsp150 was secreted slowly in both. Turning off theSEC24gene did not inhibit Hsp150 secretion either, and the lack ofSEC24expression in aΔ sfb2Δ sfb3deletant still allowed some secretion. Thesec24-1Δ sfb2Δ sfb3mutant grew slower thansec24-1. The cells were irregularly shaped, budded from random sites and contained proliferated ER at permissive temperature. At restrictive temperature, the ER formed carmellae-like proliferations. Our data indicate that ER exit may occur in vesicles lacking a full complement of Sec23p/24p and Sec13p/31p, demonstrating diversity in the composition of the COPII coat.
- Subjects
GLYCOPROTEINS; ENDOPLASMIC reticulum; SACCHAROMYCES cerevisiae; YEAST; PROTEINS; CELL proliferation
- Publication
Traffic, 2005, Vol 6, Issue 7, p562
- ISSN
1398-9219
- Publication type
Article
- DOI
10.1111/j.1600-0854.2005.00297.x