Fig. 1.

Domain organization of long RPTPβ, short RPTPβ, and phosphacan. (A) All three proteins have carbonic anhydrase (CAH) and fibronectin type III domains. Short RPTPβ lacks the bulk of the glycine-serine-rich domain encoded by exon 12. This exon also encodes sites for chondroitin sulfate–glycosaminoglycan moieties and is present in both long RPTPβ and phosphacan. Long and short RPTPβ have a short juxtamembrane region, and in short RPTPβ a unique, in-frame junction is formed in the absence of the exon 12–encoded domain. (B) Expression of both long and short RPTPβ in U373 glioblastoma. The left panel shows an immunoblot probed with RPTPβ carboxyl-terminus antibody, recognizing the intracellular region of both long and short RPTPβ. The right panel shows an immunoblot, from the same lysate, probed with antibodies specific to the short RPTPβ protein.