New fluorescence procedure leads to protein complexes in living cells

A study based on a new fluorescence anisotropy technique that examines the dynamics of large protein complexes in living cells, in real time, has been recently published (September 21st).

Issued by Cell Press in the Biophysical Journal, this commanding new method could be valuable for studying multiple different types of intracellular protein complexes.

Leading the research group, Dr Sanford M Simon, from The Rockefeller University, formed and utilised the fresh technique to study individual protein domains within a complex structure, named the nuclear pore complex (NPC).

The NPC is a bulky group of proteins that cross the double membrane that surrounds the nucleus of a cell. It controls the transfer of matter into and out of the nucleus, which contains the majority of the cell's genetic fabric.

Both rigid and flexible regions were found by the researchers, by fluorescently tagging particular domains of individual nucleoporins, the protein building blocks of the NPC.

Dr Simon explains that fluorescence anisotropy measurements of GFP-tagged nucleoporins resolved the state of order or disorder of protein domains in live maturing yeast. Also, that there were differences between different domains of the same protein.

Information on the physical arrangement of individual protein domains within the NPC can also be revealed by the technique.

The examination of different types of proteins may also benefit from the use of fluorescence anisotropy.

Provided macromolecular complexes have symmetry or are organised relative to a larger structure, fluorescence anisotropy can be universalised and applied to discern order and disorder, said Dr Simon.

"Importantly, anisotropy imaging can be accomplished in live cells, yielding a new and complementary link between structure, dynamics, and the actual function of protein complexes in their native environment," added Dr David W. Piston, from Vanderbilt University.

Posted by Ben Evans