C. Top, Binding of CDC and NDC at the vertex of 4 bent tubulin dimers of different MT nucleotide states with close-up cutaway views. Bottom, Superposition of CDC X-ray structure 5IP4 (darkened and transparent) with the GTP/GDP.Pi-MT-binding conformation (this study; bright yellow) and superposition of 5 NMR and X-ray NDC structures from Protein Data Bank (PDBs: 5IO9, 1MJD, 2BQQ, 5IKC, 5IN7) with the GDP-MT-binding conformation (this study). 