In:
American Journal of Physiology-Cell Physiology, American Physiological Society, Vol. 248, No. 5 ( 1985-05-01), p. C449-C456
Kurzfassung:
The plasma membrane-enriched fraction from dog antrum smooth muscle is enriched in ATP-dependent azide-insensitive Ca2+ uptake (0.3-0.4 microM Ca2+ required for half-maximal activity), a high-affinity Ca2+-ATPase (Km of 0.3-0.8 microM for Ca2+), a low-affinity Ca2+-ATPase (Km for 250-400 microM for Ca2+), and a Mg2+-ATPase. Studies using membranes washed with EDTA and assay media treated with Chelex 100 showed that the high-affinity Ca2+-ATPase did not depend on contaminating Mg2+. Thus, whereas the ATP-dependent Ca2+ uptake had an absolute requirement for Mg2+, the Ca2+-ATPases did not. Studies using gamma-irradiation showed that the protein responsible for the ATP-dependent Ca2+ uptake was inactivated at significantly lower doses of radiation than the three ATPases. The Ca2+ uptake and the high-affinity Ca2+-ATPase also differed in their inhibition by calmodulin antagonists and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid. Thus it is unlikely that the high-affinity Ca2+-ATPase by itself is responsible for the ATP-dependent Ca2+ uptake.
Materialart:
Online-Ressource
ISSN:
0363-6143
,
1522-1563
DOI:
10.1152/ajpcell.1985.248.5.C449
Sprache:
Englisch
Verlag:
American Physiological Society
Publikationsdatum:
1985
ZDB Id:
1477334-X
SSG:
12
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