Figure 6.

Hypothesized KS biosynthetic pathway in the absence of functional β3GnT7. We hypothesize that without operative β3GnT7, GlcNAc cannot be added to its Gal substrate (shown by a red X over GlcNAc) to form the KS repeating disaccharide. Without a terminal GlcNAc residue, perhaps the catalytic addition of Gal, GlcNAc, and sulfate cannot repeat as normal (red X over arrowed loop), resulting in an atypically shortened KS structure.