scholarly journals Identification of a carbonic anhydrase-like domain in the extracellular region of RPTP gamma defines a new subfamily of receptor tyrosine phosphatases.

1993 ◽  
Vol 13 (3) ◽  
pp. 1497-1506 ◽  
Author(s):  
G Barnea ◽  
O Silvennoinen ◽  
B Shaanan ◽  
A M Honegger ◽  
P D Canoll ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
Transmembrane Domain ◽  
Tyrosine Phosphatase ◽  
Extracellular Domain ◽  
Suppressor Gene ◽  
Tyrosine Phosphatases ◽  
Candidate Tumor Suppressor Gene ◽  
Extracellular Region ◽  
Receptor Tyrosine Phosphatases

The tyrosine phosphatase RPTP gamma is a candidate tumor suppressor gene since it is located on human chromosome 3p14.2-p21 in a region frequently deleted in certain types of renal and lung carcinomas. In order to evaluate its oncogenic potential and to explore its normal in vivo functions, we have isolated cDNAs and deduced the complete sequences of both human and murine RPTP gamma. The murine RPTP gamma gene has been localized to chromosome 14 to a region syntenic to the location of the human gene. Northern (RNA) blot analysis reveals the presence of two major transcripts of 5.5 and 8.5 kb in a variety of murine tissues. In situ hybridization analysis reveals that RPTP gamma mRNA is expressed in specific regions of the brain and that the localization of RPTP gamma changes during brain development. RPTP gamma is composed of a putative extracellular domain, a single transmembrane domain, and a cytoplasmic portion with two tandem catalytic tyrosine phosphatase domains. The extracellular domain contains a stretch of 266 amino acids with striking homology to the zinc-containing enzyme carbonic anhydrase (CAH), indicating that RPTP gamma and RPTP beta (HPTP zeta) represent a subfamily of receptor tyrosine phosphatases. We have constructed a model for the CAH-like domain of RPTP gamma based upon the crystal structure of CAH. It appears that 11 of the 19 residues that form the active site of CAH are conserved in RPTP gamma. Yet only one of the three His residues that ligate the zinc atom and are required for catalytic activity is conserved. On the basis of this model we propose that the CAH-like domain of RPTP gamma may have a function other than catalysis of hydration of metabolic CO2.

Identification of a carbonic anhydrase-like domain in the extracellular region of RPTP gamma defines a new subfamily of receptor tyrosine phosphatases

1993 ◽  
Vol 13 (3) ◽  
pp. 1497-1506
Author(s):  
G Barnea ◽  
O Silvennoinen ◽  
B Shaanan ◽  
A M Honegger ◽  
P D Canoll ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
Transmembrane Domain ◽  
Tyrosine Phosphatase ◽  
Extracellular Domain ◽  
Suppressor Gene ◽  
Tyrosine Phosphatases ◽  
Candidate Tumor Suppressor Gene ◽  
Extracellular Region ◽  
Receptor Tyrosine Phosphatases

The tyrosine phosphatase RPTP gamma is a candidate tumor suppressor gene since it is located on human chromosome 3p14.2-p21 in a region frequently deleted in certain types of renal and lung carcinomas. In order to evaluate its oncogenic potential and to explore its normal in vivo functions, we have isolated cDNAs and deduced the complete sequences of both human and murine RPTP gamma. The murine RPTP gamma gene has been localized to chromosome 14 to a region syntenic to the location of the human gene. Northern (RNA) blot analysis reveals the presence of two major transcripts of 5.5 and 8.5 kb in a variety of murine tissues. In situ hybridization analysis reveals that RPTP gamma mRNA is expressed in specific regions of the brain and that the localization of RPTP gamma changes during brain development. RPTP gamma is composed of a putative extracellular domain, a single transmembrane domain, and a cytoplasmic portion with two tandem catalytic tyrosine phosphatase domains. The extracellular domain contains a stretch of 266 amino acids with striking homology to the zinc-containing enzyme carbonic anhydrase (CAH), indicating that RPTP gamma and RPTP beta (HPTP zeta) represent a subfamily of receptor tyrosine phosphatases. We have constructed a model for the CAH-like domain of RPTP gamma based upon the crystal structure of CAH. It appears that 11 of the 19 residues that form the active site of CAH are conserved in RPTP gamma. Yet only one of the three His residues that ligate the zinc atom and are required for catalytic activity is conserved. On the basis of this model we propose that the CAH-like domain of RPTP gamma may have a function other than catalysis of hydration of metabolic CO2.

scholarly journals The Human Candidate Tumor Suppressor Gene HIC1 Recruits CtBP through a Degenerate GLDLSKK Motif

2002 ◽  
Vol 22 (13) ◽  
pp. 4890-4901 ◽  
Author(s):  
Sophie Deltour ◽  
Sébastien Pinte ◽  
Cateline Guerardel ◽  
Bohdan Wasylyk ◽  
Dominique Leprince
Keyword(s):  
Binding Site ◽  
Transcriptional Repression ◽  
Histone Deacetylases ◽  
Trichostatin A ◽  
Suppressor Gene ◽  
Close Relative ◽  
Consensus Binding Site ◽  
Candidate Tumor Suppressor Gene

ABSTRACT HIC1 (hypermethylated in cancer) and its close relative HRG22 (HIC1-related gene on chromosome 22) encode transcriptional repressors with five C2H2 zinc fingers and an N-terminal BTB/POZ autonomous transcriptional repression domain that is unable to recruit histone deacetylases (HDACs). Alignment of the HIC1 and HRG22 proteins from various species highlighted a perfectly conserved GLDLSKK/R motif highly related to the consensus CtBP interaction motif (PXDLSXK/R), except for the replacement of the virtually invariant proline by a glycine. HIC1 strongly interacts with mCtBP1 both in vivo and in vitro through this conserved GLDLSKK motif, thus extending the CtBP consensus binding site. The BTB/POZ domain does not interact with mCtBP1, but the dimerization of HIC1 through this domain is required for the interaction with mCtBP1. When tethered to DNA by fusion with the Gal4 DNA-binding domain, the HIC1 central region represses transcription through interactions with CtBP in a trichostatin A-sensitive manner. In conclusion, our results demonstrate that HIC1 mediates transcriptional repression by both HDAC-independent and HDAC-dependent mechanisms and show that CtBP is a HIC1 corepressor that is recruited via a variant binding site.

scholarly journals The primary structure of NG2, a novel membrane-spanning proteoglycan.

1991 ◽  
Vol 114 (2) ◽  
pp. 359-371 ◽  
Author(s):  
A Nishiyama ◽  
K J Dahlin ◽  
J T Prince ◽  
S R Johnstone ◽  
W B Stallcup
Keyword(s):  
Amino Acids ◽  
Chondroitin Sulfate ◽  
Primary Structure ◽  
Disulfide Bonds ◽  
Transmembrane Domain ◽  
Core Protein ◽  
Extracellular Domain ◽  
Cdna Clones ◽  
Amino Terminal ◽  
Extracellular Region

The complete primary structure of the core protein of rat NG2, a large, chondroitin sulfate proteoglycan expressed on O2A progenitor cells, has been determined from cDNA clones. These cDNAs hybridize to an mRNA species of 8.9 kbp from rat neural cell lines. The total contiguous cDNA spans 8,071 nucleotides and contains an open reading frame for 2,325 amino acids. The predicted protein is an integral membrane protein with a large extracellular domain (2,224 amino acids), a single transmembrane domain (25 amino acids), and a short cytoplasmic tail (76 amino acids). Based on the deduced amino acid sequence and immunochemical analysis of proteolytic fragments of NG2, the extracellular region can be divided into three domains: an amino terminal cysteine-containing domain which is stabilized by intrachain disulfide bonds, a serine-glycine-containing domain to which chondroitin sulfate chains are attached, and another cysteine-containing domain. Four internal repeats, each consisting of 200 amino acids, are found in the extracellular domain of NG2. These repeats contain a short sequence that resembles the putative Ca(++)-binding region of the cadherins. The sequence of NG2 does not show significant homology with any other known proteins, suggesting that NG2 is a novel species of integral membrane proteoglycan.

scholarly journals Unassisted translocation of large polypeptide domains across phospholipid bilayers

2006 ◽  
Vol 175 (5) ◽  
pp. 767-777 ◽  
Author(s):  
Silvia Brambillasca ◽  
Monica Yabal ◽  
Marja Makarow ◽  
Nica Borgese
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Transmembrane Domain ◽  
Tyrosine Phosphatase ◽  
Transmembrane Proteins ◽  
Phospholipid Bilayers ◽  
Protein Tyrosine Phosphatase 1B ◽  
Protein Insertion ◽  
Yeast Strains ◽  
The One

Although transmembrane proteins generally require membrane-embedded machinery for integration, a few can insert spontaneously into liposomes. Previously, we established that the tail-anchored (TA) protein cytochrome b(5) (b5) can posttranslationally translocate 28 residues downstream to its transmembrane domain (TMD) across protein-free bilayers (Brambillasca, S., M. Yabal, P. Soffientini, S. Stefanovic, M. Makarow, R.S. Hegde, and N. Borgese. 2005. EMBO J. 24:2533–2542). In the present study, we investigated the limits of this unassisted translocation and report that surprisingly long (85 residues) domains of different sequence and charge placed downstream of b5's TMD can posttranslationally translocate into mammalian microsomes and liposomes at nanomolar nucleotide concentrations. Furthermore, integration of these constructs occurred in vivo in translocon-defective yeast strains. Unassisted translocation was not unique to b5 but was also observed for another TA protein (protein tyrosine phosphatase 1B) whose TMD, like the one of b5, is only moderately hydrophobic. In contrast, more hydrophobic TMDs, like synaptobrevin's, were incapable of supporting unassisted integration, possibly because of their tendency to aggregate in aqueous solution. Our data resolve long-standing discrepancies on TA protein insertion and are relevant to membrane evolution, biogenesis, and physiology.

scholarly journals Structural basis for ligand-induced inactivation of protein tyrosine receptor type Z (PTPRZ): Physiological relevance of head-to-toe RPTP dimerization

2019 ◽  
Author(s):  
Akihiro Fujikawa ◽  
Hajime Sugawara ◽  
Naomi Tanga ◽  
Kentaro Ishii ◽  
Kazuya Kuboyama ◽  
...  
Keyword(s):  
Tyrosine Phosphatase ◽  
Competitive Inhibitor ◽  
Receptor Type ◽  
Structural Basis ◽  
Stoichiometric Ratio ◽  
Inhibitory Peptide ◽  
Dimer Formation ◽  
Protein Tyrosine ◽  
Extracellular Region

ABSTRACTProtein tyrosine phosphatase receptor type Z (PTPRZ) has two receptor isoforms (PTPRZ-A and -B) containing tandem PTP-D1 and -D2 domains intracellularly, with only D1 being active. Pleiotrophin (PTN) binding to the extracellular region of PTPRZ leads to the inactivation of PTPase, thereby inducing oligodendrocyte precursor cell (OPC) differentiation and myelination in the CNS. However, the mechanisms responsible for the ligand-induced inactivation of PTPRZ remain unclear. We herein revealed that the crystal structure of the intracellular region of PTPRZ (PTPRZ-ICR) showed the “head-to-toe”-type dimer conformation, with D2 masking the catalytic site of D1. Mass spectrometry (MS) revealed that PTPRZ-ICR proteins remained in monomer-dimer equilibrium in aqueous solution, and a substrate-derived inhibitory peptide or competitive inhibitor (SCB4380) specifically bound to the monomer form in a 1:1 stoichiometric ratio, supporting the “head-to-toe dimerization” model for inactivation. A D2 deletion (ΔD2) or dimer interface mutation (DDKK) disrupted dimer formation, while the binding of SCB4380 was maintained. Similar to wild-type PTPRZ-B, monomer-biased PTPRZ-B-ΔD2 and PTPRZ-B-DDKK mutants efficiently dephosphorylated p190RhoGAP at Tyr-1105 when co-expressed in BHK-21 cells. The catalytic activities of these mutants were not suppressed by a treatment with PTN, but were inhibited by the cell-permeable PTPase inhibitor NAZ2329. The PTN treatment did not enhance OPC differentiation in primary cultured glial cells prepared from ΔD2 or catalytically-inactive CS mutant knock-in mice. Our results indicate that PTN-induced PTPRZ inactivation is attained by dimer formation of the intracellular tandem PTP domains in the head-to-toe configuration, which is physiologically relevant to the control of OPC differentiation in vivo.

Oligomerization of the extracellular domain of Boss enhances its binding to the Sevenless receptor and its antagonistic effect on R7 induction

1998 ◽  
Vol 111 (6) ◽  
pp. 737-747 ◽  
Author(s):  
E.A. Sevrioukov ◽  
J.H. Walenta ◽  
A. Sunio ◽  
M. Phistry ◽  
H. Kramer
Keyword(s):  
Tyrosine Kinase ◽  
Receptor Tyrosine Kinase ◽  
Compound Eye ◽  
Transmembrane Domain ◽  
Extracellular Domain ◽  
Antagonistic Effect ◽  
Lac Repressor ◽  
Receptor Complexes

In the developing compound eye of Drosophila, neuronal differentiation of the R7 photoreceptor cell is induced by the interaction of the receptor tyrosine kinase Sevenless with its ligand Bride of sevenless (Boss), which is expressed on the neighboring R8 cell. Boss is an unusual ligand of a receptor tyrosine kinase: it is composed of a large extracellular domain, a transmembrane domain with seven membrane-spanning segments and a cytoplasmic tail. Expression of a monomeric, secreted form of the extracellular domain of Boss is not sufficient for Sevenless activation, and instead acts as a weak antagonist. Because oligomerization appears to be a critical step in the activation of receptor tyrosine kinases, we used oligomerized forms of the Boss extracellular domain to test their ability to bind to Sevenless in vivo and restore R7 induction in vivo. Oligomerization was achieved by fusion to the leucine zipper of the yeast transcription factor GCN4 or to the tetramerization helix of Lac repressor. Binding of these multivalent proteins to Sevenless could be detected in vitro by immunoprecipitation of cross-linked ligand/receptor complexes and in vivo by receptor-dependent ligand localization. However, neither R8-specific or ubiquitous expression of multivalent Exboss ligands rescued the boss phenotype. Instead, these ligands acted as competitive inhibitors for wild-type Boss protein and thereby suppressed R7 induction. Therefore the role of the transmembrane or cytoplasmic domains of Boss in the activation of the Sev receptor cannot be replaced by oligomerization.

Receptor tyrosine phosphatase R-PTP-kappa mediates homophilic binding

1994 ◽  
Vol 14 (1) ◽  
pp. 1-9
Author(s):  
J Sap ◽  
Y P Jiang ◽  
D Friedlander ◽  
M Grumet ◽  
J Schlessinger
Keyword(s):  
Tyrosine Phosphatase ◽  
Extracellular Domain ◽  
Cell Contact ◽  
Intercellular Interaction ◽  
Homophilic Binding ◽  
Fibronectin Type Iii ◽  
Immunoglobulin Domain ◽  
Receptor Tyrosine Phosphatases ◽  
Receptor Tyrosine Phosphatase ◽  
Cellular Aggregates

Receptor tyrosine phosphatases (R-PTPases) feature PTPase domains in the context of a receptor-like transmembrane topology. The R-PTPase R-PTP-kappa displays an extracellular domain composed of fibronectin type III motifs, a single immunoglobulin domain, as well as a recently defined MAM domain (Y.-P. Jiang, H. Wang, P. D'Eustachio, J.M. Musacchio, J. Schlessinger, and J. Sap, Mol. Cell. Biol. 13:2942-2951, 1993). We report here that R-PTP-kappa can mediate homophilic intercellular interaction. Inducible expression of the R-PTP-kappa protein in heterologous cells results in formation of stable cellular aggregates strictly consisting of R-PTP-kappa-expressing cells. Moreover, the purified extracellular domain of R-PTP-kappa functions as a substrate for adhesion by cells expressing R-PTP-kappa and induces aggregation of coated synthetic beads. R-PTP-kappa-mediated intercellular adhesion does not require PTPase activity or posttranslational proteolytic cleavage of the R-PTP-kappa protein and is calcium independent. The results suggest that R-PTPases may provide a link between cell-cell contact and cellular signaling events involving tyrosine phosphorylation.

scholarly journals CD45 and the immune response.

1993 ◽  
Vol 4 (4) ◽  
pp. 976-985 ◽  
Author(s):  
J A Donovan ◽  
G A Koretzky
Keyword(s):  
Signal Transduction ◽  
Amino Acids ◽  
Immune System ◽  
Single Gene ◽  
Tyrosine Phosphatase ◽  
Consensus Sequence ◽  
Extracellular Domain ◽  
In Vitro Assays

CD45 is a major transmembrane glycoprotein expressed on all nucleated hematopoietic cells. Eight isoforms of CD45 are distributed through the immune system according to cell type and degree of cellular differentiation. Heterogeneity among the isoforms is found entirely in the extracellular domain, arising from the differential splicing of up to four exons of a single gene. The control of isoform expression suggests that the extracellular domain may participate in protein-protein interactions with isoform-specific ligands. The intracellular domain of CD45 is large (approximately 700 amino acids), identical for all isoforms, and highly conserved across species. Two nonidentical intracellular sequences of about 240 amino acids that are homologous with a tyrosine phosphatase consensus sequence have been identified. Studies with purified CD45 have shown that all isoforms possess enzymatic activity in in vitro assays. In several T and B cell lines and in natural killer cells, it appears that CD45 is required for optimal signal transduction after stimulation through a number of surface receptors. Although an in vivo substrate has not been identified conclusively, one model suggests that CD45 functions to dephosphorylate a negative-regulatory tyrosine residue on one or more protein tyrosine kinases involved in receptor-mediated second messenger formation. In T cells, the src family kinases, lck and fyn, are candidates for this regulated kinase. In this review, some of the structural and functional aspects of CD45 and its role in signal transduction in the immune system are discussed.

scholarly journals PTPRM, a candidate tumor suppressor gene in small intestinal neuroendocrine tumors

2019 ◽  
Vol 8 (8) ◽  
pp. 1126-1135 ◽  
Author(s):  
Elham Barazeghi ◽  
Per Hellman ◽  
Gunnar Westin ◽  
Peter Stålberg
Keyword(s):  
Cell Growth ◽  
Tumor Suppressor ◽  
Tumor Suppressor Gene ◽  
Cell Lines ◽  
Neuroendocrine Tumors ◽  
Tyrosine Phosphatase ◽  
Suppressor Gene ◽  
Cpg Methylation ◽  
Candidate Tumor Suppressor Gene ◽  
Small Intestinal

Small intestinal neuroendocrine tumors (SI-NETs) are small, slow growing neoplasms with loss of one copy of chromosome 18 as a common event. Frequently mutated genes on chromosome 18 or elsewhere have not been found so far. The aim of this study was to investigate a possible tumor suppressor role of the transmembrane receptor type tyrosine phosphatase PTPµ (PTPRM at 18p11) in SI-NETs. Immunohistochemistry, quantitative RT-PCR, colony formation assay and quantitative CpG methylation analysis by pyrosequencing were performed. Undetectable/very low levels of PTPRM or aberrant pattern of immunostaining, with both negative and positive areas, were detected in the majority of tumors (33/40), and a significantly reduced mRNA expression in metastases compared to primary tumors was observed. Both the DNA methylation inhibitor 5-aza-2′-deoxycytidine and the S-adenosylhomocysteine hydrolase inhibitor 3-deazaneplanocin A (DZNep) induced PTPRM expression in CNDT2.5 and KRJ-I SI-NET cells. CpG methylation of upstream regulatory regions, the promoter region and the exon 1/intron 1 boundary was detected by pyrosequencing analysis of the two cell lines and not in the analyzed SI-NETs. Overexpression of PTPRM in the SI-NET cell lines reduced cell growth and cell proliferation and induced apoptosis. The tyrosine phosphatase activity of PTPRM was not involved in cell growth inhibition. The results support a role for PTPRM as a dysregulated candidate tumor suppressor gene in SI-NETs and further analyses of the involved mechanisms are warranted.

Identification and characterization of the STIM (stromal interaction molecule) gene family: coding for a novel class of transmembrane proteins

2001 ◽  
Vol 357 (3) ◽  
pp. 673-685 ◽  
Author(s):  
Richard T. WILLIAMS ◽  
Shehnaaz S. M. MANJI ◽  
Nigel J. PARKER ◽  
Manuela S. HANCOCK ◽  
Leonie van STEKELENBURG ◽  
...  
Keyword(s):  
Single Gene ◽  
Coiled Coil ◽  
Suppressor Gene ◽  
Tumour Suppressor Gene ◽  
Protein Sequencing ◽  
Ancestral Gene ◽  
Cdna Sequences ◽  
Extracellular Region ◽  
Chromosome 11P15.5

STIM1 (where STIM is stromal interaction molecule) is a candidate tumour suppressor gene that maps to human chromosome 11p15.5, a region implicated in a variety of cancers, particularly embryonal rhabdomyosarcoma. STIM1 codes for a transmembrane phosphoprotein whose structure is unrelated to that of any other known proteins. The precise pathway by which STIM1 regulates cell growth is not known. In the present study we screened gene databases for STIM1-related sequences, and have identified and characterized cDNA sequences representing a single gene in humans and other vertebrates, which we have called STIM2. We identified a single STIM homologue in Drosophila melanogaster (D-Stim) and Caenorhabditis elegans, but no homologues in yeast. STIM1, STIM2 and D-Stim have a conserved genomic organization, indicating that the vertebrate family of two STIM genes most probably arose from a single ancestral gene. The three STIM proteins each contain a single SAM (sterile α-motif) domain and an unpaired EF hand within the highly conserved extracellular region, and have coiled-coil domains that are conserved in structure and position within the cytoplasmic region. However, the STIM proteins diverge significantly within the C-terminal half of the cytoplasmic domain. Differential levels of phosphorylation appear to account for two molecular mass isoforms (105 and 115kDa) of STIM2. We demonstrate by mutation analysis and protein sequencing that human STIM2 initiates translation exclusively from a non-AUG start site in vivo. STIM2 is expressed ubiquitously in cell lines, and co-precipitates with STIM1 from cell lysates. This association into oligomers in vivo indicates a possible functional interaction between STIM1 and STIM2. The structural similarities between STIM1, STIM2 and D-STIM suggest conserved biological functions.

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