Figure 8.

Model illustrating HS and CS binding to RPTPσ. HSPGs on the same cell interact in cis with RPTPσ through the novel binding sites near the transmembrane domain and regulate the enzymatic activity of RPTPσ, resulting in the altered Tyr phosphorylation of certain sets of proteins and the recognition of HS as a permissive cue. When CS/DS GAGs are presented in trans, binding occurs through the first Ig domain far from the transmembrane domain and triggers the changes in phosphorylation of distinct sets of proteins within the cells, resulting in the recognition of CS/DS as an inhibitory cue by RPTPσ.