%0 Journal Article
%T Ca~(2+)-MEDIATED CHANGE IN LIPID FLUIDITY MODULATES THE RECONSTITUTED SARCOPLASMIC RETICULUM Ca~(2+)-ATPase ACTIVITY<br>Ca~(2+)通过膜脂影响肌质网Ca~(2+)-ATP酶的活性与Ca~(2+)转运功能
%A 汪戈
%A 杨福愉
%J 生物物理学报
%D 1988
%I 
%X Ca2 + -ATPase from sarcoplasmic reticulum was reconstituted into the soybean phospholipid vesicles with the freeze-thawing mathod.Four types of proteoliposomes containing sarcoplasmic reticulum Ca2+-ATPase have been prepared; Ca2+-"free" ,L.(Ca2+-ATPase) ;outside Ca2+-containing, L.(Ca2+-ATPase) ; inside Ca2+-containing,L. (Ca2+-ATPase) and two-side Ca2+-containing,L.(Ca2+-ATPase) proteoliposomes. L.(Ca2+-ATPase) was prepared by ATP driven Ca2+ pumping from outside into the interior of the proteoliposomes. Being chelated by EGTA the outside Ca2+ of the vesicles, the L. (Ca2+-ATPase) was transformed into the L. (Ca2+ -ATPase) .The fluidity of the proteoliposomes has been compared by fluorescence polarization probes diphenylhexatriene (DPH) or 7-, 12-, 16-(9-anthroyloxy)stearic acid (7, 12, 16-AS). The degree of polarization in these proteoliposomes decreases in the order.L.(Ca2+-ATPase) >L.(Ca2+-ATPase) >L.(Ca2+-ATPase) >L.(Ca2+-ATPase) .Concomitantly with the lipid fluidity measurements the ATP driven Ca2+ transport and Ca2+-ATPase activity were also monitored. It was interested to note that as the proteoliposomes were loaded with Ca2+ due to ATP driven Ca2+ pumping, the reconstituted Ca2+-ATPase activity as well as the Ca2+ transport was gradually inhibited. The ATP hydrolysis rate of Ca2+-ATPase containing proteoliposomes in the 4th minute was only 9% of that in the 1st minute. However, no similar inhibition was observed when the activity of purified non-incorporating Ca2+-ATPase was determined under the same experimental conditions. So, it seems that the reconstituted Ca2+-ATPase activity in liposomes may be modulated by the Ca2+-mediated changing fluidity of the lipid bilayer, resulting from the variation of transmembrane Ca2+ concentration gradient.
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=90BA3D13E7F3BC869AC96FB3DA594E3FE34FBF7B8BC0E591&jid=E0C9D9BBED813D6674AC13E942EAC86D&aid=D7190F8DAFA0CC52ADAF82EE92D24507&yid=0702FE8EC3581E51&vid=E158A972A605785F&iid=0B39A22176CE99FB&sid=4DB1E72614E68564&eid=EDA22B444205D04A&journal_id=1000-6737&journal_name=生物物理学报&referenced_num=1&reference_num=0