Conservation of functional domains in plant and animal SUN-domain proteins. Comparative diagrams of SUN-domain proteins depicting protein sizes and domain locations (see Table 2). The positions of transmembrane (red), coiled-coil (blue), SUN (yellow), and PM3-associated (PAD) domains (black) are indicated for each protein. (A) Known nonplant SUN-domain proteins (human, Hs; mouse, Mm; nematode; Ce; fission yeast, Sp) of various sizes, but all with a single C-terminal SUN domain are shown (UniProt accession numbers: HsSUN1, O94901; HsSUN2, Q9UH99; MmSUN1, Q9D666; MmSUN2, Q8BJS4; CeSUN1, Q20924; CeUNC84, Q20745; SpSAD1, Q09825). (B) CCSD and (C) PM3 plant proteins grouped by their orthologous groups (see Figure 1).