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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The wall-associated kinases (WAK), a family of five proteins that contain extracellular domains that can be linked to pectin molecules of the cell wall, span the plasma membrane and have a cytoplasmic serine/threonine kinase domain. Previous work has shown that a reduction in WAK protein levels leads to a loss of cell expansion, indicating that these receptor-like proteins have a role in cell shape formation. Here it is shown that a single wak2 mutation exhibits a dependence on sugars and salts for seedling growth. This mutation also reduces the expression and activity of vacuolar invertase, often a key factor in turgor and expansion. WAKs may thus provide a molecular mechanism linking cell wall sensing (via pectin attachment) to regulation of solute metabolism, which in turn is known to be involved in turgor maintenance in growing cells.
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PMID:An Arabidopsis cell wall-associated kinase required for invertase activity and cell growth. 1662 92

Recent evidence indicates that several mechanisms can alter invertase activity and, thus, affect sucrose metabolism and resource allocation in plants. One of these mechanisms is the compartmentalisation of at least some vacuolar invertases in precursor protease vesicles (PPV), where their retention could control timing of delivery to vacuoles and hence activity. PPV are small, ER-derived bodies that sequester a subset of vacuolar-bound proteins (such as invertases and protease precursors) releasing them to acid vacuoles in response to developmental or environmental signals. Another newly-identified effector of invertases is wall-associated kinase 2 (WAK2), which can regulate a specific vacuolar invertase in Arabidopsis (AtvacINV1) and alter root growth when osmolyte supplies are limiting. WAKs are ideally positioned to sense changes in the interface between the cell wall and plasma membrane (such as turgor), because the N-terminus of each WAK extends into the cell wall matrix (where a pectin association is hypothesised) and the C-terminus has a cytoplasmic serine/threonine kinase domain (signalling). Still other avenues of invertase control are provided by a diverse group of kinases and phosphatases, consistent with input from multiple sensing systems for sugars, pathogens, ABA and other hormones. Mechanisms of regulation may also vary for the contrasting sugar responses of different acid invertase transcripts. Some degree of hexokinase involvement and distinctive kinetics have been observed for the sugar-repressed invertases, but not for the more common, sugar-induced forms examined thus far. An additional means of regulation for invertase gene expression lies in the multiple DST (Down STream) elements of the 3' untranslated region for the most rapidly repressed invertases. Similar sequences were initially identified in small auxin-up RNAs (SAUR) where they mediate rapid mRNA turnover. Finally, the invertase inhibitors, cell wall- and vacuolar inhibitors of fructosidase (CIF and VIF, respectively) are indistinguishable by sequence alone from pectin methylesterase inhibitors (PMEI); however, recent evidence suggests binding specificity may be determined by flexibility of a short, N-terminal region. These recently characterised processes increase the suite of regulatory mechanisms by which invertase - and, thus, sucrose metabolism and resource partitioning - can be altered in plants.
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PMID:Regulation of invertase: a 'suite' of transcriptional and post-transcriptional mechanisms. 3268 79