| 1. |
- Knapp, S, et al.
(författare)
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Thermal unfolding of small proteins with SH3 domain folding pattern
- 1998
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Ingår i: Proteins. - 0887-3585 .- 1097-0134. ; 31:3, s. 309-319
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Tidskriftsartikel (refereegranskat)abstract
- The thermal unfolding of three SH3 domains of the Tec family of tyrosine kinases was studied by differential scanning calorimetry and CD spectroscopy, The unfolding transition of the three protein domains in the acidic pH region can be described as a reversible two-state process. For all three SH3 domains maximum stability was observed in the pH region 4.5 < pH < 7.0 where these domains unfold at temperatures of 353K (Btk), 342K (Itk), and 344K (Tec), At these temperatures an enthalpy change of 196 kJ/mol, 178 kJ/mol, and 169 kJ/mol was measured for Btk-, Itk-, and Tec-SH3 domains, respectively. The determined changes in heat capacity between the native and the denatured state are in an usual range expected for small proteins. Our analysis revealed that all SH3 domains studied are only weakly stabilized and have free energies of unfolding which do not exceed 12-16 kJ/mol but show quite high melting temperatures. Comparing unfolding free energies measured for eukaryotic SH3 domains with those of the topologically identical Sso7d protein from the hyperthermophile Sulfolobus solfataricus, the increased melting temperature of the thermostable protein is due to a broadening as well as a significant lifting of its stability curve. However, at their physiological temperatures, 310K for mesophilic SH3 domains and 350K for Sso7d, eukaryotic SH3 domains and Sso7d show very similar stabilities. (C) 1998 Wiley-Liss, Inc.
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| 2. |
- Smith, C I E, et al.
(författare)
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The Tec family of cytoplasmic tyrosine kinases : mammalian Btk, Bmx, Itk, Tec, Txk and homologs in other species
- 2001
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Ingår i: Bioessays. - : Wiley. - 0265-9247 .- 1521-1878. ; 23:5, s. 436-446
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Tidskriftsartikel (refereegranskat)abstract
- Cytoplasmic protein-tyrosine kinases (PTKs) are enzymes involved in transducing a vast number of signals in metazoans, The importance of the Tec family of kinases was immediately recognized when, in 1993, mutations in the gene encoding Bruton's tyrosine kinase (Btk) were reported to cause the human disease X-linked agammaglobulinemia (XLA).((1,2)) Since then, additional kinases belonging to this family have been isolated, and the availability of full genome sequences allows identification of all members in selected species enabling phylogenetic considerations. Tec kinases are endowed with Pleckstrin homology (PH) and Tec homology (TH) domains and are involved in diverse biological processes related to the control of survival and differentiation fate, Membrane translocation resulting in the activation of Tec kinases with subsequent Ca2+ release seems to be a general feature, However, nuclear translocation may also be of importance, the purpose of this essay is to characterize members of the Tec family and discuss their involvement in signaling. The three-dimensional structure, expression pattern and evolutionary aspects will also be considered.
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