SILAC

[
right|thumb|420px|The principle of SILAC. Cells differentially labeled by growing them in light medium with normal arginine (Arg-0, grey colour) or medium with heavy arginine (Arg-6, red colour). Metabolic incorporation of the amino acids into the proteins results in a mass shift of the corresponding peptides. This mass shift can be detected by a mass spectrometer as indicated by the depicted mass spectra. When both samples are combined, the ratio of peak intensities in the mass spectrum reflects the relative protein abundance. In this example, the labeled protein has the same abundance in both samples (ratio 1).] SILAC (Stable isotope labelling with amino acids in cell culture) is a mass spectrometry-based technique developed to detect differences in protein abundance between two (or more) samples (Ong et al., 2002). It is one of the most popular methods for quantitative proteomics. Two populations of cells are cultivated in cell culture. One of the cell populations is fed with growth medium containing normal amino acids. In contrast, the growth medium of the second cell population contains amino acids labeled with stable (non-radioactive) heavy isotopes. For example, the medium can contain arginine labeled with six carbon-13 atoms (¹³C) instead of the normal carbon-12 (¹²C). When the cells are growing in this medium, they incorporate the heavy arginine into all of their proteins. Therefore, all of the arginine containing peptides are now 6 Da heavier than their normal counterparts. The trick is that the proteins from both cell populations can be combined and analyzed together by mass spectrometry. Pairs of chemically identical peptides of different stable-isotope composition can be differentiated in a mass spectrometer owing to their mass difference. The ratio of peak intensities in the mass spectrum for such peptide pairs accurately reflects the abundance ratio for the two proteins. SILAC has emerged as a very powerful method to study cell signaling, protein-protein interaction and regulation of gene expression.

References

*cite journal
author=Ong SE, Blagoev B, Kratchmarova I, Kristensen DB, Steen H, Pandey A, Mann M | date=2002
title=Stable isotope labeling by amino acids in cell culture, SILAC, as a simple and accurate approach to expression proteomics
journal=Molecular & Cell Proteomics
volume=1
pages=376–86
pmid=12118079
url=http://www.mcponline.org/cgi/content/abstract/1/5/376
doi=10.1074/mcp.M200025-MCP200

*cite journal
author=Ong SE, Kratchmarova I, Mann M | date=2003
title=Properties of 13C-substituted arginine in stable isotope labeling by amino acids in cell culture (SILAC)
journal=Journal of Proteome Research
volume=2
pages=173–81
pmid=12716131
url=http://pubs.acs.org/cgi-bin/abstract.cgi/jprobs/2003/2/i02/abs/pr0255708.html
doi=10.1021/pr0255708

*cite journal
author=Ong SE, Mann M | date=2006
title=A practical recipe for stable isotope labeling by amino acids in cell culture (SILAC)
journal=Nature Protocols
volume=1
pages=2650–60
pmid=17406521
url=http://www.nature.com/nprot/journal/v1/n6/abs/nprot.2006.427.html;jsessionid=A1C175998EF7868150C7EB074268ED06
doi=10.1038/nprot.2006.427

*cite journal
author=Ong SE, Mann M | date=2007
title=Stable isotope labeling by amino acids in cell culture for quantitative proteomics
journal=Methods in Molecular Biology
volume=359
pages=37–52
pmid=17484109

ee also

* Cell signaling
* mass spectrometry
* Protein-protein interaction
* Proteomics
* ITRAQ

External links

* [http://www.biochem.mpg.de/en/research/rd/mann/approaches/silac/index.html SILAC resource Mann Lab]
* [http://www.silac.org SILAC resource Pandey Lab]
* [http://www.pil.sdu.dk/silac.htm SILAC resource Center for Experimental Bioinformatics (CEBI)]