Resumen:
rotein palmitoylation is a post-translational modification
that affects a great number of proteins. In most cases, the
enzymes responsible for this modification have not been
identified. Some proteins use palmitoylation to attach
themselves to membranes; however, palmitoylation also
occurs in transmembrane proteins, and the function of this
palmitoylation is less clear. Here we identify Swf1, a
member of the DHHC-CDR family of palmitoyltransferases,
as the protein responsible for modifying the yeast SNAREs
Snc1, Syn8 and Tlg1, at cysteine residues close to the
cytoplasmic end of their single transmembrane domains
(TMDs). In an swf1D mutant, Tlg1 is mis-sorted to the
vacuole. This occurs because unpalmitoylated Tlg1 is
recognised by the ubiquitin ligase Tul1, resulting in its
targeting to the multivesicular body pathway. Our results
suggest that one role of palmitoylation is to protect TMDs
from the cellular quality control machinery, and that Swf1
may be the enzyme re