our research project involves the characterization of a particular signal transduction pathway. Specifically, you have been studying a receptor tyrosine kinase and protein Z, which initiates downstream events. You are certain that protein Z is part of the signal transduction pathway, but have been unable to identify a direct protein-protein interaction between the receptor tyrosine kinase and the protein Z. What should you do next in your attempt to identify a link between the receptor tyrosine kinase and protein Z