Figure 5: SPEF1 is a seam-binding protein.

(A) Diagram of the tip CP highlighting SPEF1A (green). α-Tubulin is light gray, and β-tubulin is dark gray. (B) Model of SPEF1A interacting with tubulin at the seam. (C, D) Amino acids that likely mediate the interaction between α-(C) and β-(D) tubulin. The equivalent amino acids in β- and α-tubulin are shown in blue in (C) and in green in (D), respectively. (E) Alignment of Tetrahymena SPEF1A_1–86, SPEF1B, human SPEF1 (UniProtID Q9Y4P9) and Chlamydomonas FAP178 (UniProtID A0A2K3D8Z6). The amino acids shown in C and D are highlighted with a green asterisk.