scholarly journals TAK1-binding protein 1 is a pseudophosphatase

2006 ◽  
Vol 399 (3) ◽  
pp. 427-434 ◽  
Author(s):  
Sarah H. Conner ◽  
Gursant Kular ◽  
Mark Peggie ◽  
Sharon Shepherd ◽  
Alexander W. Schüttelkopf ◽  
...  
Keyword(s):  
Metal Binding ◽  
Protein Phosphatase ◽  
Transforming Growth Factor ◽  
Binding Protein ◽  
Structural Similarity ◽  
Transforming Growth Factor Β ◽  
Titration Calorimetry ◽  
Regulatory Subunits ◽  
Nitrophenyl Phosphate ◽  
Dual Metal

TAB1 [TAK1 (transforming growth factor-β-activated kinase 1)-binding protein 1] is one of the regulatory subunits of TAK1, a protein kinase that lies at the head of three pro-inflammatory kinase cascades. In the current study we report the crystal structure of the N-terminal domain of TAB1. Surprisingly, TAB1 possesses a fold closely related to that of the PPM (Mg2+- or Mn2+-dependent protein phosphatase) family as demonstrated by the close structural similarity with protein phosphatase 2Cα. However, we were unable to detect any phosphatase activity for TAB1 using a phosphopeptide or p-nitrophenyl phosphate as substrate. Although the overall protein phosphatase 2Cα fold is conserved in TAB1, detailed structural analyses and mutagenesis studies show that several key residues required for dual metal-binding and catalysis are not present in TAB1, although binding of a single metal is supported by soaking experiments with manganese and isothermal titration calorimetry. Thus, it appears that TAB1 is a ‘pseudophosphatase’, possibly binding to and regulating accessibility of phosphorylated residues on substrates downstream of TAK1 or on the TAK1 complex itself.

scholarly journals SARP, a new alternatively spliced protein phosphatase 1 and DNA interacting protein

2007 ◽  
Vol 402 (1) ◽  
pp. 187-196 ◽  
Author(s):  
Gareth J. Browne ◽  
Margarida Fardilha ◽  
Senga K. Oxenham ◽  
Wenjuan Wu ◽  
Nicholas R. Helps ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Mammalian Cells ◽  
Leucine Zipper ◽  
Transforming Growth Factor ◽  
Binding Protein ◽  
Transforming Growth Factor Β ◽  
Ankyrin Repeat ◽  
Protein Phosphatase 1 ◽  
Binding Motif ◽  
Alternative Mrna Splicing

PP1 (protein phosphatase 1) is a ubiquitously expressed serine/threonine-specific protein phosphatase whose activity towards different substrates appears to be mediated via binding to specific proteins that play critical regulatory and targeting roles. In the present paper we report the cloning and characterization of a new protein, termed SARP (several ankyrin repeat protein), which is shown to interact with all isoforms of PP1 by a variety of techniques. A region encompassing a consensus PP1-binding motif in SARP (K354VHF357) modulates endogenous SARP–PP1 activity in mammalian cells. This SARP–PP1 interaction motif lies partially within the first ankyrin repeat in contrast with other proteins [53BP2 (p53 binding protein 2), MYPT1/M110/MBS (myosin binding protein of PP1) and TIMAP (transforming growth factor β inhibited, membrane-associated protein)], where a PP1-binding motif precedes the ankyrin repeats. Alternative mRNA splicing produces several isoforms of SARP from a single human gene at locus 11q14. SARP1 and/or SARP2 (92–95 kDa) are ubiquitously expressed in all tissues with high levels in testis and sperm, where they are shown to interact with both PP1γ1 and PP1γ2. SARP3 (65 kDa) is most abundant in brain where SARP isoforms interact with both PP1α and PP1γ1. SARP is highly abundant in the nucleus of mammalian cells, consistent with the putative nuclear localization signal at the N-terminus. The presence of a leucine zipper near the C-terminus of SARP1 and SARP2, and the binding of mammalian DNA to SARP2, suggests that SARP1 and SARP2 may be transcription factors or DNA-associated proteins that modulate gene expression.

Abstract 32: Investigating the Autoactivation of p38α Mitogen-Activated Protein Kinase Mediated by Transforming Growth Factor-β-Activated Protein Kinase Binding Protein 1

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Gian Felice De Nicola ◽  
E D Martin ◽  
Rekha Bassi ◽  
Sharwari Verma ◽  
Maria Conte ◽  
...  
Keyword(s):  
Growth Factor ◽  
Protein Kinase ◽  
Transforming Growth Factor ◽  
Binding Protein ◽  
Transforming Growth Factor Β ◽  
Mitogen Activated Protein Kinase ◽  
Scaffolding Protein ◽  
Titration Calorimetry ◽  
Activation Loop

Activation of p38α MAPK (p38α), by phosphorylation of two residues in the TGY motif of the activation loop, can occur independently of upstream kinases. One such mechanism involves the scaffolding protein Transforming Growth Factor-β-activated protein kinase binding protein 1 (TAB1). Under certain circumstances, such as myocardial ischemia, this activation can aggravate lethal injury. It is one of a few examples of activating autophosphorylation and poses a conundrum. How does an inactive kinase, and therefore with low affinity for ATP, phosphorylate its own activation loop when ATP binding is a prerequisite step for phosphotransfer? The aim of this study was to characterize the TAB1 binding of p38α. The binding characteristics of p38α and TAB1 were determined by Isothermal Titration Calorimetry, followed by the binding of p38α and ATPγS, a slowly hydrolysable form of ATP, in the presence and absence of TAB1. The binding of TAB1 to p38α increased significantly the affinity of p38α for ATP. Following the identification of a key region in TAB1 responsible for p38α binding, a synthetic peptide encompassing this region was used to analyze the biophysical and biological consequences of TAB1 binding. In vitro kinase assays were used to test the biochemical characteristics using a combination of wildtype kinase, kinase dead (K53M) or both in the absence or presence of TAB1(371-416). Using an antibody specific to the dual phosphorylation of the TGY motif as a readout, TAB1 binding to p38α increased p38α autophosphorylation in cis . NMR was employed to map the interaction surfaces between of p38α and TAB1 and to analyze the effect of TAB1-binding on p38α. The residues identified as important for the interaction between TAB1 and p38α were mutated and tested in cell free and biological systems to confirm their role as critical determinants for binding. In conclusion, we have further elucidated a mechanism whereby TAB1 binding to p38α alters the conformation of p38α, increasing its affinity for ATP and thereby facilitating autophosphorylation. We have identified the binding contacts of TAB1 and p38α that may be important in the design of therapeutics enabling selective and circumstance-specific inhibition of p38α activation.

Versican G1 and G3 domains are upregulated and latent transforming growth factor-β binding protein-4 is downregulated in breast cancer stroma

Breast Cancer ◽  
2011 ◽  
Vol 19 (1) ◽  
pp. 46-53 ◽  
Author(s):  
Yuko Takahashi ◽  
Hiroko Kuwabara ◽  
Masahiko Yoneda ◽  
Zenzo Isogai ◽  
Nobuhiko Tanigawa ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Growth Factor ◽  
Transforming Growth Factor ◽  
Binding Protein ◽  
Transforming Growth Factor Β ◽  
Cancer Stroma

Latent transforming growth factor-β binding protein-1 LTBP1

1998 ◽  
pp. 178-180
Author(s):  
Shirley Ayad ◽  
Ray Boot-Handford ◽  
Martin J. Humphries ◽  
Karl E. Kadler ◽  
Adrian Shuttleworth
Keyword(s):  
Growth Factor ◽  
Transforming Growth Factor ◽  
Binding Protein ◽  
Transforming Growth Factor Β
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