You down with GGT?


Hello everyone. Welcome back to my blog.  It’s been a while but I’m here again, ready to throw out a bit of knowledge to help you get the most out of your cells, and in this case, maybe even help you avoid getting ripped off. So what better way to do that than to talk about Gamma-Glutamyltransferase? I know. I have goosebumps, too.

Gamma-Glutamyltransferase (GGT) is an enzyme that has several functions and is found in varying levels in whole blood and serum. It helps to transfer amino acids across the cell membrane and is involved in glutathione synthesis.  It’s also an important clinical marker. GGT is typically elevated in many diseases and can be used to diagnose alcohol-related liver disease in patients. In most mammals, it is transferred from mom to newborn baby (or calf) from colostrum contributing to innate immunity.

So why is GGT concentration such an important value to understand if you’re a cell biologist?  My friends at Gemini always list GGT levels on their Certificates of Analysis, so I’m glad you asked!

Way back in 1993, Hanigan and colleagues published a letter to the editor in the journal “In Vitro Cellular and Developmental Biology-Animals.” They noticed that they were having trouble reproducing some experiments. In their words they “obtained anomalous results.” Given that they knew of GGT’s role in glutathione synthesis, they asked whether different lots of serum used in their experiments had different levels of GGT. What they found was that FBS typically shows GGT levels of less than 5 IU/L while serum from newborn calves (NCS) had levels ranging from 13 to 365 IU/L. What they learned was that high GGT levels in serum has profound effects on cells in vitro. To Hanigan and colleagues, it was a matter of figuring out how to properly control their experiments by vetting their serum supply.

But to some nefarious entities we all have the potential to encounter, this was a warning (even if they didn’t know it at the time). Some companies have made a practice of substituting the much less expensive NCS for high cost FBS and labeling it “FBS.” In short, people were getting ripped off and in the process suffering an even worse fate of not being able to objectively analyze their data. Data they worked long and hard to collect. So in part, nowadays, people tend to look at GGT levels, especially if they suspect that the guy with the bargain basement FBS prices is up to some funny business.  So next time you are presented with a price for FBS that’s too good to be true, don’t hesitate to respond with “Show me the GGT!”