Modulators of actin-myosin dissociation: Basis for muscle type functional differences during fatigue
Επιτομή
The muscle types present with variable fatigue tolerance, in part due to the myosin isoform expressed. However, the critical steps that define “fatigability” in vivo of fast vs. slow myosin isoforms, at the molecular level, are not yet fully understood. We examined the modulation of the ATP-induced myosin subfragment 1 (S1) dissociation from pyrene-actin by inorganic phosphate (Pi), pH, and temperature using a specially modified stopped-flow system that allowed fast kinetics measurements at physiological temperature. We contrasted the properties of rabbit psoas (fast) and bovine masseter (slow) myosins (obtained from samples collected from New Zealand rabbits and from a licensed abattoir, respectively, according to institutional and national ethics permits). To identify ATP cycling biochemical intermediates, we assessed ATP binding to a preequilibrated mixture of actomyosin and variable [ADP], pH (pH 7 vs. pH 6.2), and Pi (zero, 15, or 30 added mM Pi) in a range of temperatures (5 to 45°C). Temperature and pH variations had little, if any, effect on the ADP dissociation constant (KADP) for fast S1, but for slow S1, KADP was weakened with increasing temperature or low pH. In the absence of ADP, the dissociation constant for phosphate (KPi) was weakened with increasing temperature for fast S1. In the presence of ADP, myosin type differences were revealed at the apparent phosphate affinity, depending on pH and temperature. Overall, the newly revealed kinetic differences between myosin types could help explain the in vivo observed muscle type functional differences at rest and during fatigue. © the American Physiological Society
Collections
Related items
Showing items related by title, author, creator and subject.
-
Transient up- and down-regulation of expression of myosin light chain 2 and myostatin mRNA mark the changes from stratified hyperplasia to muscle fiber hypertrophy in larvae of gilthead sea bream (Sparus aurata L.)
Georgiou S., Alami-Durante H., Power D.M., Sarropoulou E., Mamuris Z., Moutou K.A. (2016)Hyperplasia and hypertrophy are the two mechanisms by which muscle develops and grows. We study these two mechanisms, during the early development of white muscle in Sparus aurata, by means of histology and the expression ... -
Polyclonal hypergammaglobulinemia and high smooth-muscle autoantibody titers with specificity against filamentous actin: consider visceral leishmaniasis, not just autoimmune hepatitis
Makaritsis, K. P.; Gatselis, N. K.; Ioannou, M.; Petinaki, E.; Dalekos, G. N. (2009)Visceral leishmaniasis (VL) remains a public health problem in most countries bordering the Mediterranean basin. Its diagnosis is challenging and often delayed, as the main clinical picture is often indistinguishable from ... -
Alpha-actinin: A multidisciplinary protein with important role in B-cell driven autoimmunity
Kikonomou, K. G.; Zachou, K.; Dalekos, G. N. (2011)Alpha-actinin (α-actinin) is a ubiquitous cytoskeletal protein, which belongs to the superfamily of filamentous actin (F-actin) crosslinking proteins. It is present in multiple subcellular regions of both muscle and ...