Figure 1.

Eleven hexapeptide repeats in the aggrecan sequence [70] (starting with glutamic acid (E)) are proposed to form an extended polyproline-II-like (threefold) helix. Each hexamer is then approximately 1.86 nm long. This indicates that the KS-chains, which form a twofold helix, all project on one side and their sulphates on alternate sides form a highly anionic plane of dimensions approximately 20 × 20 nm. KS-chain diagrams are adapted from diagrams published CC-BY by Selberg et al. [73].