DSP family

The classical PTPs can be subdivided into receptorlike PTPs and nonreceptor, cytosolic PTPs. The second category of PTPs are broadly defined as dual specificity phosphatases (DSPs), which dephosphorylate pSer/ pThr as well as pTyr. MAP kinase phosphatases (MKPs) ( MAP kinase cascades) and PTEN are examples of DSP family members. Remarkably, PTEN also has lipid phosphatase activity that is specific for phosphatidylinositol-3,4,5-trisphosphate generated in response to the actions of PI3K. Finally, the class of low molecular mass (LM-) PTPs and that of CDC25 PTPs accomplish the cells repertoire of PTPs (Fig. 3). 

Cutshall et al. [41] have synthesized a series of rhodanine-based inhibitors and tested against the dual-specificity phosphatases (DSP) family member c-fim N-terminal kinases (JNK)-stimulating phosphatase-1 QSP-l). The SAR studies demonstrated that presence of stronger electron-withdrawing functional groups at aryl-benzylidene position provided analogs with the greatest potencies as illustrated by compound (XXXVIII). These derivatives may be useful for the treatment of inflammatory and proliferative disorders. 

Diarrheic Shellfish Poisoning (DSP). Human poisonings were first identified in the 1960s. It causes sickness in humans lasting several days but is not fatal. It is caused by chemicals of the okadaic acid family (okadaic acid+ 4 related compounds) produced by several species of Dinophysis dinoflagellates. The main contamination problems include mussels, clams, and other bivalves of the cold and warm temperate areas of the Atlantic and Pacific Oceans, mainly in Japan and Europe. Only two cases of DSP have been documented in North America. 

The azaspiracids (AZAs) are a new group of toxins identified in 1995 during an outbreak in the Netherlands, when symptoms of DSP poisoning were observed, but with very low concentration of OA and DTX in shellfish [60]. After purification, it was possible to identify this family of new toxins called azaspiracids [61]. 

Cellular responses to the OA family of DSP toxins can differ enormously, and sometimes yield opposite effects, depending on the concentration of the toxin, the length of exposure to the toxin, and the cell type. In general, an acute exposiffe of cells to moderate or high concentrations of OA... 

DSP (CazSKCHsCHzCOOjfi) Family Ca2Sr(CH CH2C00)(, (DSP) (LB Number 58A-1). This crystal is ferroelectric below about 4°C (Fig. 4.5-82). The Curie-Weiss constant is small (60 K). Critical slowing-down (see Sect. 4.5.3) takes place (Fig. 4.5-8). 

Layer-structure family 28 NaNOa family (2, 2 1) 58 DSP (Ca2Sr(CH3CH2COO)6)... 

Another family of diolefins in which a similar reaction was observed is that of phenylene diacrylic acid 2 and its derivatives. These also undergo lattice-controlled polymerization, and the very close relationship between the packing of the diacrylic acids, cinnamic acid, and DSP is shown in Figure 6.1. 

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