Palmitoylation of type-two membrane proteins in yeast and mammalian cells.

GONZALEZ MONTORO A; FERRARI M; VALDEZ TAUBAS J

Mar del Plata, Buenos Aires Argentina

Congreso; XLIII SAIB; 2007

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Many proteins are modified by the addition of a palmitate to a cysteine residue. Hydrophilic proteins such as G proteins or Ras, use this modification to attach to membranes. However, many transmembrane proteins are also palmitoylated and the function of this modification is less clear. A family of transmembrane proteins sharing a motif called DHHC-CRD (Asp-His-His-Cys ?Cysteine Rich Domain) is involved in most protein S-acylation events described so far. Swf1, a yeast member of the DHHC family has been implicated in membrane-associated palmitoylation of SNARE proteins and Golgi Glycosyltranferases (GTs), both type-two membrane proteins. We have focused our study into the C-terminal domain of Swf1 predicted to be cytosolic. Within this region, we have identified a novel motif, conserved in some DHHC proteins, that is essential for Swf1 function. Site-directed mutagenesis allowed us to identify a tyrosine residue within this motif as critical for Swf1 function. We have also shown that this C terminal domain is able to bind palmitoyl-CoA. Palmitoylation of SNARE proteins or GTs has not been described in mammalian cells nor has the Swf1 orthologue. We have evidence that at least some SNARES are similarly palmitolylated. Experiments are underway to extend this observation to GTs, to identify the Swf1 orthologue and to study the functional consequences of this modification.