The Effect of Truncated Troponin Components on Activation of Lethocerus Flight Muscle

摘要: Indirect flight muscle (IFM) of Lethocerus is activated by periodic stretches at a constant priming concentration calcium. The unusually stiff and stress transmitted to the thick thin filaments kettin, which reinforces links between both Z-disc. activating effect on likely affect troponin. isoforms troponin in IFM differ from those other muscles. TnT has C-terminal extension not present vertebrate TnT; TnH an isoform TnI with rich Pro Ala; TnC two isoforms: F1 binds single calcium C-lobe needed for stretch-activation; F2 one N- C-lobes isometric force. Under conditions low ionic strength, native fibres have force-pCa curve that shows high calcium-sensitivity cooperativity (pCa50 = 6.2, nH 1.3). Fibres alone pCa similar cardiac muscle, 5.8, 3.2). A fragment without N-lobe (F1-Ct) inhibits therefore necessary, although it does bind or TnH. F1-Ct displaced force restored, but stretch-activation. We hope show replacing endogenous complex containing truncated C-terminus, sequence Pro-Ala extension, either F2. This will how important are stretch-activation response.