Protein fatty acyltransferase is located in the rough endoplasmic reticulum

The fatty acid acylation of polypeptides was studied in vivo and in vitro by incorporation of radiolabeled palmitic acid into Semliki Forest viral polypeptides. Utilizing a cell-free system for acylation protein fatty acyltransferase was characterized as an integral membrane protein. No acylation activity was detected in the cytosol. During subcellular fractionation of a variety of mammalian or avian cells the enzyme was localized to the rough endoplasmic reticulum. Therefore this posttranslational hydrophobic modification starts earlier in the biosynthesis of acylated polypeptides than previously believed.