06 April 2016 ICFO on the cover of Chemistry Select

Single molecule fluorescence reveals dimerization of the oncogene Src. The tyrosine-protein kinase Src is a key element of signaling cascades involved in the invasive and metastasis-forming capacity of cancer cells. Researchers Bruno Castro and Erik Garbacik working in the Single Molecule Biophotonics group led by ICREA Professor at ICFO Maria Garcia-Parajo in collaboration with the Institute for Research in Biomedicine (IRB-Barcelona)* and the University of Barcelona discovered that dimerization of Src may constitute a new regulation layer for the Src oncogene. This discovery has made the cover of the April issue of Chemistry Select.

Src is a paradigmatic non-receptor kinase involved in signaling pathways related to cell migration, proliferation and survival. Since overexpression and overactivation of Src have been associated to cancer progression and poor clinical prognosis, Src constitutes a major oncologic target. In contrast to membrane tyrosine-kinase receptors, which are known to dimerize in order to initiate signaling, Src is classified as a non-receptor kinase and assumed to remain always monomeric.

Using single molecule fluorescence photobleaching methods, the ICFO team has now discovered that a fraction of c-Src molecules spontaneously form dimers only when they are anchored to the membrane surface. Moreover, a co-existence between monomers and dimers was observed which was independent on the protein concentrations used. Switching from monomers to dimers might constitute a new mechanism for the efficient location of specific sites on the membrane surface from which c-Src signaling takes place.

**ICFO and IRB are both members of the Barcelona Institute of Science and Technology.