Összesen 2 találat.


001-es BibID:BIBFORM049067
035-os BibID:PMID:9854019
Első szerző:Szegedi Csaba
Cím:Calsequestrin : more than 'only' a luminal Ca2+ buffer inside the sarcoplasmic reticulum / Csaba Szegedi, Sarkozi Sandor, Anke Herzog, Istvan Jóna, Magdolna Varsanyi
Megjegyzések:In striated muscle, the sarcoplasmic reticulum (SR) Ca2+ release/ryanodine receptor (RyR) channel provides the pathway through which stored Ca2+ is released into the myoplasm during excitation-contraction coupling. Various luminal Ca2+-binding proteins are responsible for maintaining the free [Ca2+] at 10(-3)-10(-4) M in the SR lumen; in skeletal-muscle SR, it is mainly calsequestrin. Here we show that, depending on its phosphorylation state, calsequestrin selectively controls the RyR channel activity at 1 mM free luminal [Ca2+]. Calsequestrin exclusively in the dephosphorylated state enhanced the open probability by approx. 5-fold with a Hill coefficient (h) of 3.3, and increased the mean open time by about 2-fold, i.e. solely dephosphorylated calsequestrin regulates Ca2+ release from the SR. Because calsequestrin has been found to occur mainly in the phosphorylated state in the skeletal-muscle SR for the regulation of RyR channel activity, the dephosphorylation of calsequestrin would appear to be a quintessential physiological event.
Tárgyszavak:Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Biochemical Journal. - 337 : Pt. 1 (1999), p. 19-22. -
További szerzők:Sárközi Sándor (1966-) (élettanász) Herzog, Anke Jóna István (1948-) (élettanász, fizikus) Varsányi Magdolna
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat


001-es BibID:BIBFORM049068
035-os BibID:PMID:11943213
Első szerző:Varsányi Magdolna
Cím:Troponin I converts the skeletal muscle ryanodine receptor into a rectifying calcium release channel / Magdolna Varsányi, Sándor Sárközi, Csaba Szegedi, Anke Herzog, István Jóna
Megjegyzések:The goal of our present studies has been to find novel ryanodine receptor (RyR1) interacting polypeptides that modulate the channel activity from the luminal side of RyR1. Using K(+) as charge carrier for recording of single channel events here we demonstrate a very unexpected observation that troponin I substantially alters RyR's gating behavior, and that RyR1 in association with troponin I becomes a rectifying Ca(2+) release channel. Troponin I rapidly locks the RyR1 in a non-conducting state only at a negative holding potential, and only when applied to the luminal side; switching to a positive holding potential results in the channel returning to its original activity, immediately. A hypothesis is proposed to account for how an intraluminally located, positively charged molecule might function as a RyR1 regulator under physiological conditions.
Tárgyszavak:Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:FEBS Letters. - 515 : 1-3 (2002), p. 155-158. -
További szerzők:Sárközi Sándor (1966-) (élettanász) Szegedi Csaba Herzog, Anke Jóna István (1948-) (élettanász, fizikus)
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
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