Schmidtmann Anja, Lohmann Karin, Jaquet Kornelia
Physiologische Chemie, Abt. Biochemie Supramolekularer Systeme, Medizinische Fakultät, Ruhr-Universität Bochum, MA 2/39, 44780, Bochum, Germany.
FEBS Lett. 2002 Feb 27;513(2-3):289-93. doi: 10.1016/s0014-5793(02)02340-2.
Cardiac troponin I, the inhibitory subunit of the heterotrimeric cardiac troponin (cTn) complex is phosphorylated by protein kinase A at two serine residues located in its heart-specific N-terminal extension. This flexible arm interacts at different sites within cTn dependent on its phosphorylation degree. Bisphosphorylation is known to induce conformational changes within cTnI which finally lead to a reduction of the calcium affinity of cTnC. However, as we show here, the bisphosphorylated cTnI arm does not interact with cTnC, but with cTnT and/or cTnI.
心肌肌钙蛋白I是异三聚体心肌肌钙蛋白（cTn）复合物的抑制亚基，它在位于其心脏特异性N端延伸区的两个丝氨酸残基处被蛋白激酶A磷酸化。这个柔性臂根据其磷酸化程度在cTn内的不同位点相互作用。已知双磷酸化会诱导cTnI内的构象变化，最终导致cTnC对钙的亲和力降低。然而，正如我们在此所展示的，双磷酸化的cTnI臂并不与cTnC相互作用，而是与cTnT和/或cTnI相互作用。
