Co-IP analysis of SINE1/2–AtSUN interactions. (A) Domain organization of SINE1, SINE2, and their KASH domain mutants. The C-terminal 4 aa are indicated in bold. (B) Domain organization of AtSUN2 and its mutants. The C-terminal 30 aa of AtSUN2 are shown, and the residues changed in AtSUN2dMut are indicated in red. Diagrams in A and B were drawn to scale, with the gaps in A representing 300 aa. The numbers above each domain indicate the position of the first and the last amino acid of that domain. Magenta, domain N-terminal to the TMD of SINE1 or SINE2; blue, domain N-terminal to the TMD of AtSUN2; yellow, TMD; white, unknown domain; red, coiled-coil domain; green, N-terminal part of the SUN domain; orange, C-terminal part of the SUN domain. (C) SINE1 and SINE2 interact with AtSUN1 through their KASH domain. (D) SINE1 and SINE2 interact with AtSUN2 through their KASH domain. (E–G) AtSUN1 and AtSUN2 interact with SINE1 and SINE2 through their SUN domain. The asterisk in the bottom right of E indicates the codetected GFP-Myc-AtSUN2ΔNSUN band. In C–G, GFP-tagged proteins were immunoprecipitated and detected with anti-GFP antibodies. Myc-tagged proteins were detected with an anti-Myc antibody. The input/IP ratio is 1:9.