| タイトル | A novel calmodulin-regulated Ca2+-ATPase (ACA2) from Arabidopsis with an N-terminal autoinhibitory domain |
| 著者（英） | Palmgren, M. G.; Huang, J. F.; Harper, J. F.; Hong, B.; Sze, H.; Evans, M. L.; Hwang, I.; Stoddard, R.; Guo, H. Q. |
| 発行日 | 1998-01-09 |
| 言語 | eng |
| 内容記述 | To study transporters involved in regulating intracellular Ca2+, we isolated a full-length cDNA encoding a Ca2+-ATPase from a model plant, Arabidopsis, and named it ACA2 (Arabidopsis Ca2+-ATPase, isoform 2). ACA2p is most similar to a "plasma membrane-type" Ca2+-ATPase, but is smaller (110 kDa), contains a unique N-terminal domain, and is missing a long C-terminal calmodulin-binding regulatory domain. In addition, ACA2p is localized to an endomembrane system and not the plasma membrane, as shown by aqueous-two phase fractionation of microsomal membranes. ACA2p was expressed in yeast as both a full-length protein (ACA2-1p) and an N-terminal truncation mutant (ACA2-2p; Delta residues 2-80). Only the truncation mutant restored the growth on Ca2+-depleted medium of a yeast mutant defective in both endogenous Ca2+ pumps, PMR1 and PMC1. Although basal Ca2+-ATPase activity of the full-length protein was low, it was stimulated 5-fold by calmodulin (50% activation around 30 nM). In contrast, the truncated pump was fully active and insensitive to calmodulin. A calmodulin-binding sequence was identified within the first 36 residues of the N-terminal domain, as shown by calmodulin gel overlays on fusion proteins. Thus, ACA2 encodes a novel calmodulin-regulated Ca2+-ATPase distinguished by a unique N-terminal regulatory domain and a non-plasma membrane localization. |
| NASA分類 | Life Sciences (General) |
| 権利 | Copyright |
| URI | https://repository.exst.jaxa.jp/dspace/handle/a-is/297264 |
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