Figure 5. A study by co-immunoprecipitation (Co-IP) to identify the binding partners of MARK4 in adult rat testes. Using about 800 μg protein of lysates from adult rat testes for each Co-IP reaction as described in Materials and Methods with the corresponding antibodies, MARK4 was found to structurally interact with β-tubulin and desmosomal armadillo protein plakophilin-2, but not with any actin-based adhesion proteins at the basal ES (e.g., β-catenin), apical ES (e.g., Eps 8) and TJ (e.g., occludin, Eps8). T lysate, testis lysate; IP, immunoprecipitation; IB, immunoblotting; Rb, rabbit; Gt, goat; Ctrl, control; IgG, immunoglobulin G; (+), positive protein-protein interaction; (-), negative protein-protein interaction.