Nucleotide sequence and molecular variants of rat receptor-type protein tyrosine phosphatase-/β

Abstract

We have previously described the cloning of phosphacan, a chondroitin sulfate proteoglycan of nervous tissue which interacts with neurons, glia, neural cell adhesion molecules, and tenascin, and represents the extracellular domain of a receptor-type protein tyrosine phosphatase. We now report the complete cDNA and deduced amino acid sequences of the rat transmembrane phosphatase, and demonstrate that the phosphatase and the extracellular proteoglycan have different 3'-untranslated regions. Northern analysis showed three probable splice variants, comprising the extracellular proteoglycan (phosphacan) and long and short forms of the transmembrane phosphatase. PCR studies of rat genomic DNA indicated that there are no introns at the putative 5' and 3' splice sites or in the 2.6 kb segment which is deleted in the short transmembrane protein. Using variant-specific riboprobes corresponding to sequences in the 3'-untranslated region of phosphacan and in the first or second phosphatase domains of the transmembrane protein, in situ hybridization histochemistry of embryonic rat brain and spinal cord and early postnatal cerebellum demonstrated identical localizations of phosphacan and phosphatase mRNAs.

Complex-type Asparagine-linked Oligosaccharides on Phosphacan and Protein-tyrosine Phosphatase-ζ/β Mediate Their Binding to Neural Cell Adhesion Molecules and Tenascin

“…Cloning of phosphacan (Maurel et al, 1994) demonstrated that it is an alternative splicing product representing the entire extracellular domain of a receptor-type protein-tyrosine phosphatase (RPTP) 1 named RPTP/␤ (Krueger and Saito, 1992;Levy et al, 1993;Maurel et al, 1995). A keratan sulfate-containing glycoform (phosphacan-KS) also occurs in postnatal brain (Rauch et al, 1991;Maurel et al, 1994;MeyerPuttlitz et al, 1995).…”

The Fibrinogen-like Globe of Tenascin-C Mediates Its Interactions with Neurocan and Phosphacan/Protein-tyrosine Phosphatase-ζ/β

“…It contains N-terminal immunoglobulin-like and hyaluronanbinding domains, a C-terminal domain consisting of EGF-, lectin-, and complement regulatory protein-like sequences, and a nonhomologous central domain of 593 amino acids, which contains the attachment sites for the three chondroitin sulfate chains and a large number of O-glycosidic oligosaccharides. In contrast, phosphacan (4,5), which contains a 173-kDa core protein and three chondroitin sulfate chains, is an mRNA splicing product that represents the entire extracellular domain of a receptor-type protein-tyrosine phosphatase that also occurs as a chondroitin sulfate proteoglycan in brain (3). Phosphacan and protein-tyrosine phosphatase /␤ have an N-terminal carbonic anhydrase-like domain followed by a fibronectin type III sequence.…”

Protein tyrosine phosphatase hPTPN20a is targeted to sites of actin polymerization

“…Two other PTP genes, encoding the intracellular STEP (striatal enriched phosphatase) [42,43] and the transmembrane receptor-like RPTPζ /β [44][45][46] are alternatively spliced to generate proteins that lack catalytic domains. No information is available as to the function of the STEP variant [42,43], but the RPTPζ /β variant is secreted and may have distinct, as well as competitive, possibly dominant-negative, functions with respect to full-length transmembrane RPTPζ /β [47][48][49][50][51].…”