These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Interplay between the overlapping ends of tropomyosin and the N terminus of cardiac troponin T affects tropomyosin states on actin.
    Author: Mamidi R, Michael JJ, Muthuchamy M, Chandra M.
    Journal: FASEB J; 2013 Sep; 27(9):3848-59. PubMed ID: 23748972.
    Abstract:
    The functional significance of the molecular swivel at the head-to-tail overlapping ends of contiguous tropomyosin (Tm) dimers in striated muscle is unknown. Contractile measurements were made in muscle fibers from transgenic (TG) mouse hearts that expressed a mutant α-Tm (Tm(H276N)). We also reconstituted mouse cardiac troponin T (McTnT) N-terminal deletion mutants, McTnT(1-44Δ) and McTnT(45-74Δ), into muscle fibers from Tm(H276N). For controls, we used the wild-type (WT) McTnT because altered effects could be correlated with the mutant forms of McTnT. Tm(H276N) slowed crossbridge (XB) detachment rate (g) by 19%. McTnT(1-44Δ) attenuated Ca(2+)-activated maximal tension against Tm(WT) (36%) and Tm(H276N) (38%), but sped g only against Tm(H276N) by 35%. The rate of tension redevelopment decreased (17%) only in McTnT(1-44Δ) + Tm(H276N) fibers. McTnT(45-74Δ) attenuated tension (19%) and myofilament Ca(2+) sensitivity (pCa50=5.93 vs. 6.00 in the control fibers) against Tm(H276N), but not against Tm(WT) background. Thus, altered XB cycling kinetics decreased the fraction of strongly bound XBs in McTnT(1-44Δ) + Tm(H276N) fibers, whereas diminished thin-filament cooperativity attenuated tension in McTnT(45-74Δ) + Tm(H276N) fibers. In summary, our study is the first to show that the interplay between the N terminus of cTnT and the overlapping ends of contiguous Tm effectuates different states of Tm on the actin filament.
    [Abstract] [Full Text] [Related] [New Search]