FnTm is a novel transmembrane protein found to be up-regulated in the learning system in birds and other mammals. Identifying FnTm protein partners will allow us to clarify the FnTm signaling pathway in the brain. However, identifying protein pairs is often limited because the weak forces by which proteins interact are not sufficient to preserve the protein�macromolecule complex. To circumvent this limitation we are working towards introducing a photocross-linkable non-natural analog of para-azidophenylalanine and photoleucine in a residue-specific manner into FnTm. Here we demonstrate the progress of our efforts to discover the protein�protein interactions involved in learning.