Figure 1

Typical septin structure. Septin sequences range from about three hundred to six hundred amino acids. Septins contain the conserved GTP_CDC binding domain with three motifs: G1, GxxxxGK [ST] (amino acids 126–135 in S. cerevisiae Cdc3p); G3, DxxG (amino acids 204–209 in S. cerevisiae Cdc3p); and G4, xKxD (amino acids 280–289 in S. cerevisiae Cdc3p). The previously described polybasic region (amino acids 110–120 in S. cerevisiae Cdc3p; [19, 21]) is shown as a black box and the previously described "septin unique element" (amino acids 360–413 in S. cerevisiae Cdc3p [21]); is shown as a grey box. S1-S4 mark positions of new septin motifs (Table 2b; amino acid 237–242, 247–259, 261–268, 364–365 in S. cerevisiae Cdc3p) and lines below diagram show conserved single amino acid positions (Table 2c; amino acids 117, 295, 300, 339, 360, 396 in S. cerevisiae Cdc3p). Many septins also have a predicted coiled-coil domain at the C-terminus (amino acids 476–507 in S. cerevisiae Cdc3p; [21]).