...to identify the molecules that interact with the primary magnetic sensors and the molecules in a downstream signalling cascade that eventually trigger a change in the membrane potential of the primary signalling cascade. We identified six putative protein interaction partners of European robin cryptochrome 4a, which all code for retina specific proteins. We therefore focus on characterising cryptochrome mediated binding processes using biochemical and biophysical methods including protein-membrane interaction processes. Our studies also aim at characterising the trigger events that start initiate the downstream signalling cascade.