FEBS Letters | |
Phosphorylation of chicken brain‐type creatine kinase affects a physiologically important kinetic parameter and gives rise to protein microheterogeneity in vivo | |
Quest, Andrew F.G.1  Perriard, Jean-Claude1  Soldati, Thierry1  Wallimann, Theo1  Hemmer, Wolfram1  Eppenberger, Hans M.1  | |
[1]Institute for Cell Biology, ETH-Hönggerberg, CH-8093 Zurich, Switzerland | |
关键词: Phosphorylation of creatine kinase; Regulation of creatine kinase activity; Intracellular ATP level; Energetics; The term B-CK stands for the dimeric brain-type creatine kinase isoenzyme (enzymatically active form). Bb; Ba; Bb∗ and Bbl-3 represent different B-CK monomers; | |
DOI : 10.1016/0014-5793(90)81215-A | |
学科分类:生物化学/生物物理 | |
来源: John Wiley & Sons Ltd. | |
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【 摘 要 】
In addition to the two monomer subunits of chicken brain-type creatine kinase (B-CK, EC, 2.7.3.2), termed Bb (basic) and Ba (acidic), another subspecies called Bb∗ was identified by chromatofocussing in the presence of 8 M urea (Quest et al., [20]). The latter low abundance protein species, isolated from tissue extracts, comigrated on 2D-gels with three minor species (Bbl-3), initially identified in immunoprecipitated, [35S]methionine labeled in vitro translation products of cDNA coding for the basic monomer Bb. During in vitro translation experiments in the presence of [32P]-γ -ATP, Bbl-3 were labeled while phosphatase treatment eliminated these minor species. It is concluded that Bb* is identical to Bbl-3 and represents phosphorylated derivatives of Bb. B-CK dimer populations from different tissues were separated by ion-exchange chromatography and the Km values of the resulting fractions were determined under phospho-creatine (CP)-limiting conditions. In fractions containing only Bb and Bb∗ two kinetically different enzyme species were detected (Km values for CP = 1.6 mM and 0.8 mM), while fractions containing B-CK dimers composed of the major Ba and Bb monomers, but no Bb∗, were homogeneous in this respect (Km for CP = 1.6 mM). Phosphorylation of Bb to yield Bb∗ is concluded to reduce the Km of B-CK dimers for CP by about 50%. This Km shift is within the range of CP concentrations found in tissues expressing the B-CK isoform and may therefore be of physiological relevance.
【 授权许可】
Unknown
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