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Novel Golgi to vacuole delivery pathway in yeast: identification of a sorting determinant and required transport component
Author(s) -
Cowles Christopher R.,
Snyder William B.,
Burd Christopher G.,
Emr Scott D.
Publication year - 1997
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/16.10.2769
Subject(s) - biology , golgi apparatus , vacuole , component (thermodynamics) , yeast , microbiology and biotechnology , sorting , identification (biology) , protein targeting , saccharomyces cerevisiae , vesicular transport proteins , computational biology , genetics , membrane protein , vacuolar protein sorting , endoplasmic reticulum , cytoplasm , botany , membrane , physics , computer science , programming language , thermodynamics
More than 40 vacuolar protein sorting ( vps ) mutants have been identified which secrete proenzyme forms of soluble vacuolar hydrolases to the cell surface. A subset of these mutants has been found to show selective defects in the sorting of two vacuolar membrane proteins. Under non‐permissive conditions, vps45 tsf ( SEC1 homolog) and pep12/vps6 tsf (endosomal t‐SNARE) mutants efficiently sort alkaline phosphatase (ALP) to the vacuole while multiple soluble vacuolar proteins and the membrane protein carboxypeptidase yscS (CPS) are no longer delivered to the vacuole. Vacuolar localization of ALP in these mutants does not require transport to the plasma membrane followed by endocytic uptake, as double mutants of pep12 tsf and vps45 tsf with sec1 and end3 sort and mature ALP at the non‐permissive temperature. Given the demonstrated role of t‐SNAREs such as Pep12p in transport vesicle recognition, our results indicate that ALP and CPS are packaged into distinct transport intermediates. Consistent with ALP following an alternative route to the vacuole, isolation of a vps41 tsf mutant revealed that at non‐permissive temperature ALP is mislocalized while vacuolar delivery of CPS and CPY is maintained. A series of domain‐swapping experiments was used to define the sorting signal that directs selective packaging and transport of ALP. Our data demonstrate that the amino‐terminal 16 amino acid portion of the ALP cytoplasmic tail domain contains a vacuolar sorting signal which is responsible for the active recognition, packaging and transport of ALP from the Golgi to the vacuole via a novel delivery pathway.