IMAGE: This is an illustration showing the ‘Cluedo’ game of proprotein convertase activity. view more
Credit: D.B. Constam/EPFL
Most proteins in the cell are not produced “ready to go”. Instead, they are first synthesized with chains of amino acids that block their activity until they are removed by enzymes called “proprotein convertases” (PCs). This family of enzymes plays significant but very different roles in various cancers, and regulating the activity of PCs could help develop cancer treatments. But PCs overlap in terms of activity, meaning that two or more of these enzymes can process the same protein. This overlap makes it very difficult to distinguish and map out the functional profile of each PC.
One important aspect of a PC’s life is its trafficking in secretory vesicles to the cell surface, and its internalization in endosomes that mediate re-cycling to the so-called trans-Golgi network, a trafficking hub where secretory vesicles and endosomes exchange protein cargo, and where PC’s have been thought to perform most of their protein-activating work.
The lab of Daniel Constam at ISREC (EPFL) has now developed targeted biosensors that can image specific PCs on a subcellular level, thereby overcoming the problems of overlap. The biosensors are
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