KASH5 interacts with SUN1/2 via the KASH domain. (A) Immunoprecipitates (IP) from mouse testis using a SUN1 antibody (Ab.) or control (Cont.) IgG were analyzed by immunoblot using the indicated antibodies. Total soluble extract (0.1%) was loaded as input. (B) Yeast two-hybrid assay using KASH5 fragments. T-antigen (T) and p53 act as a positive control. C, C-terminal region; M, middle region; N, N-terminal region; TM, transmembrane.