Bacterial lipoproteins, which carry an S-linked diacylglycerol motif, have previously been probed using tagging approaches in Escherichia coli [ 62]; optimized quantitative methods click here should be widely applicable in a variety of pathogenic bacteria, to further illuminate the functional roles of this key bacterial machinery in virulence. Interplay with lipid metabolism: lipid metabolism is known to be dysregulated in many cancers and as a consequence of therapy

(e.g. statin or fatty acid synthase inhibitor treatment), and there is recent evidence that tissue-specific lipid metabolism directly impacts the profile of protein lipidation [ 63]. The potential for incorporation of branched lipids, unsaturated fatty acids and cholesterol-related learn more hormones remains almost unexplored at present, and the combination of lipidomics with tagging approaches, as recently explored for prenylation [ 53•], is likely to reveal a complex interplay between these systems. Imaging specific protein lipidation: the widespread nature of lipids in the cell,

both in membranes and on proteins, renders global analysis by cellular imaging of limited utility; even in an ideal case, only the overall distribution of lipids and/or lipidated proteins is revealed [ 64]. An exception is cholesterylation which appears to be uniquely attached to Hh proteins; following clearance of membrane lipids, this modification only can be imaged with

good fidelity [ 17••]. In the first step towards a more general methodology, Gao and Hannoush, recognizing that substrate-specific imaging requires protein identity coupled to covalent modification by a lipid, employed a combination of palmitoyl tagging and specific antibodies coupled to oligonucleotides, enabling proximity-directed detection by rolling-circle amplification [ 65]. Preliminary studies suggest that with optimization this rather complex approach is capable of direct detection of palmitoylation of Wnt, Hh and Ras proteins [ 66••], but significant technological hurdles remain if this approach is to be rendered generally applicable, or of use in live cell imaging.