Contributes to the assembly of the acentrosomal spindle and phragmoplast microtubule arrays as part of the augmin complex. Regulates the association of gamma-tubulin with the spindle and phragmoplast microtubules. Part of the augmin complex composed of 8 subunits. The complex acts on microtubules and interacts with gamma-tubulin in spindles and the phragmoplast. Preferentially localizes to microtubules minus ends.