5 September 2005: The cell cycle colour coded

Researchers in Switzerland and Germany have developed a set of colourful tools for characterising surface proteins on living cells. Proteins can be sequentially labelled, the researchers report, enabling multicolour imaging of dynamic processes, such as protein secretion.

The new technique relies on the covalent modification of so-called carrier proteins that bind to the cell surface proteins being investigated. Cell surface proteins are secreted and fixed at certain positions during the cell cycle. Proteins secreted at different times are located at different regions of the cell surface.

Nils Johnsson at the University of Muenster and colleagues tested the technique in yeast. They found that, by labelling the carrier proteins with different coloured fluorophores at different time intervals, a colour-coded, time-dependent map of the cell cycle emerged. 

The researchers developed two methods. The first involves labelling each protein with a different colour as it is secreted; the second selectively labels the different cell surface proteins at the same time. 

Developing the imaging techniques was straightforward, said Johnsson. ’Once we realised how well [acyl carrier protein] fusion proteins are secreted to the cell surface there were no big problems to overcome,’ he told Chemistry World. ’This should be seen as an invitation to other scientists to use this technique,’ he added.

’We would like to take the step from characterising proteins in isolated cells to characterising them in tissues or whole organisms,’ said Johnsson. ’Which approach will be suited best to achieve this goal or whether we need a totally different approach is still a matter of active debate between our two labs,’ he concluded. Katharine Sanderson