Using a new tool allowing proteins in a living cell to be manipulated in real time, researchers at Johns Hopkins have stumbled across the answer to a long-standing debate about where and how a certain protein is turned on in the cell. Reporting in the February 2012 issue of Nature Chemical Biology, scientists show that protein kinase A is also activated in the nucleus rather than inside the cell’s body, a challenge to traditional beliefs.
“People have been wondering about nuclear PKA and [the answer] clicked when we saw our results,” says Jin Zhang, Ph.D, associate professor of pharmacology at Johns Hopkins. For the most part, those in the field believe that PKA is activated in the cell’s cytoplasm, but there is conflicting evidence suggesting it could also be present in the nucleus. Zhang says the answer to the debate clicked for her team when a cell biology technique gave them unusual results.
According to Zhang, PKA has always been thought to be activated outside the nucleus. Upon activation, it travels into the nucleus to turn on the cell’s response. Zhang’s data showed the signal from PKA activated at the cell’s edge is slow in reaching the inside of nucleus, so the only explanation for a fast response at the nucleus would be if another population of PKA was already there.
“We’re collecting information that shows PKA at the nucleus is functional, it’s not contamination and not background signal,” says Zhang. “These are real functional enzymes that can be activated.”
Edited from Happy accident answers cell signal controversy.