Figure 3. Somatic mutations identified in the Ig1-Ig2 tandem repeats of type IIa RPTPs. Mutations in LAR, PTPRD and PTPRS are shown on the structure of human LAR bound to the glycosaminoglycan mimic sucrose octasulfate (PDB ID 2YD8⁶⁹). The sucrose octasulfate is shown in ball-and-stick representation. The residues that are mutated in cancers are shown as spheres colored based on the predicted effects of the location of the mutations (yellow, buried; green, interdomain interface; red, ligand interface; white, solvent exposed). The expected effect of the mutations in yellow would be to disrupt the folding of the Ig domain while mutation of the residues colored green is expected to disrupt the interface between Ig1 and Ig2. Introducing a glycine to glutamate change at position 61 (shown in red in the structure) is expected to impair interactions with the ligand. The potential effects of mutating residues colored white are unknown.