Figure 4. Topology of the TTLL5 protein and approximate location of all reported mutations. There are 4 major domains in the TTLL5 protein: the TTLL core domain that binds to ATP; an overlapping c-terminal microtubule binding domain (c-MTBD) that interacts with microtubulins; a linker region, followed by a cofactor interaction domain (CID) that interacts with to RPGR^orf15; and a receptor interaction domain (RID) of unknown function. Bold-type numbers identify the amino acid (aa) position relative to the location of each domain. Arrowhead: Mutations identified in this study. Double arrowhead lines represent previously reported large deletions in the TTLL5 protein.