Role of a Ca2+-ATPase induced by ABA and IAA in the generation of specific Ca2+ signals.

The control of the Ca(2+)-ATPase gene (LCA1) that encodes two different membrane-located isoforms by two antagonic phytohormones, ABA and IAA, has been investigated. Strikingly both the growth regulators induce the LCA1 expression. By using a protoplast transient system, the cis-acting DNA elements responding to both, abiotic stress (ABA) and normal development (IAA), are dissected.

Do untranslated introns control Ca2+-ATPase isoform dependence on CaM, found in TN and PM?

Transcript splicing characterization of tomato Ca(2+)-ATPase (LCA1 gene) mRNA indicates that two main transcripts are differentiated in the 3(') terminal region. One of them contains a sequence of about 90bp that could correspond to an untranslated intron that displays sequence homology to calmodulin-binding regions. Calmodulin-binding experiments demonstrate that only one of the two isoforms encoded by LCA1 binds to calmodulin.

Yeast inositol mono- and trisphosphate levels are modulated by inositol monophosphatase activity and nutrients.

Yeast lithium-sensitive inositol monophosphatase (IMPase) is encoded by a non-essential gene pair (IMP1 and IMP2). Inhibition of IMPase with either Li(+) or Na(+) or a double null mutation imp1 imp2 causes increased levels of inositol monophosphates and reduced level of inositol 1,4,5-trisphosphate. Overexpression of the IMP2 gene has the opposite effects and these results suggest that IMPase activity is limiting for the inositol cycle.