Figure 8. Hypothetical mechanism of SAS-5 function.
(A) SAS-5 forms tight dimers in the cytoplasm, and it may also associate with SAS-6 dimers depending on the relative levels of each protein. (B) SAS-5 localizes at the centriole, where it forms higher-order assemblies. These assemblies bring together multiple SAS-6 dimers in close proximity to one another, thereby increasing the local SAS-6 concentration. Thus, SAS-5 assemblies create a seeding point from which the SAS-6 oligomer forms (C); the first step in creating the C. elegans central tube.