The KASH domain of KASH5 and inner NE protein SUN1 are required for telomere localization of KASH5. (A) Schematic representations of GFP-tagged KASH5 mutants. TM, transmembrane. (B) Spermatocytes from the testis transfected with GFP-tagged KASH5 mutants were stained with GFP and SCP3 antibodies. (C) Pachytene spermatocytes of wild-type (WT) and SUN1 KO mice were stained by the indicated antibodies. The top images show the localization of KASH5 signals (anti-KASH5 antibody) in the areas boxed in the bottom images. Note that KASH5 localization to telomeres was abolished in SUN1 KO mice. Bars, 5 µm.