Alain Mareck

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Pectin methylesterases (PMEs) were detected in tobacco (Nicotiana tabacum) pollen tubes grown in vitro. Seven PME isoforms exhibiting a wide isoelectric-point (pI) range (5.3–9.1) were found in crude extracts of pollen tubes. These isoforms were mainly retrieved in supernatants after low- and high-speed separation of the crude extract. Two isoforms, with(More)
In the course of a study on the early events of cambial derivative differentiation in Populus × euramericana, seasonal changes in the pattern of pectin methylesterase (PME, EC isoforms were followed. During the resting season, cell wall extracts contained mainly alkaline isoforms with an Mr around 55 kDa and optimal pH between 5.6 and 6.0. Neutral(More)
Pectin methylesterases (PMEs, EC catalyse the deesterification of pectins. Up to now, most information concerning their location was obtained from biochemical analyses. Taking advantage of specific anti-PME antibodies, we report the precise localization of PMEs at the electron microscopy level within the different cortical tissues of flax(More)
Pectin methylesterases (PMEs) are ubiquitous enzymes present in the plant cell wall. They catalyse the demethylesterification of homogalacturonic acid units of pectins, which, in turn, can be associated with different physiological phenomena. In this study, different flax (Linum usitatissimum L.) PME isoforms were observed: neutral (pI 7.0 and 7.5, MW: 110(More)
BACKGROUND AND AIMS In Arabidopsis thaliana, the degree of methylesterification (DM) of homogalacturonans (HGs), the main pectic constituent of the cell wall, can be modified by pectin methylesterases (PMEs). In all organisms, two types of protein structure have been reported for PMEs: group 1 and group 2. In group 2 PMEs, the active part (PME domain,(More)
An Arabidopsis thaliana pectin methylesterase that was not predicted to contain any signaling sequence was produced in E. coli and purified using a His tag added at its N-terminus. The enzyme demethylesterified Citrus pectin with a K m of 0.86 mg/ml. The enzyme did not require salt for activity and was found to be relatively temperature-sensitive. The(More)
Developmental changes in the composition of brain microtubule-associated proteins have been studied in three species: the rat and the mouse, which are characterized by post-natal brain development, and the guinea-pig, whose brain is mature at birth. 1. At an adult stage, and whatever the species, two major microtubule-associated proteins, which have been(More)
Pectin methylesterase (PME) catalyses the de-methylesterification of pectin in plant cell walls during cell elongation. (1) Pectins are mainly composed of α(1, 4)-D-galacturonosyl acid units that are synthesised in a methylesterified form in the Golgi apparatus to prevent any interaction with Ca2+ ions during their intracellular transport. (2) The highly(More)
• Here, we focused on the biochemical characterization of the Arabidopsis thaliana pectin methylesterase 3 gene (AtPME3; At3g14310) and its role in plant development. • A combination of biochemical, gene expression, Fourier transform-infrared (FT-IR) microspectroscopy and reverse genetics approaches were used. • We showed that AtPME3 is ubiquitously(More)
Germination of pollen grains is a crucial step in plant reproduction. However, the molecular mechanisms involved remain unclear. We investigated the role of PECTIN METHYLESTERASE48 (PME48), an enzyme implicated in the remodeling of pectins in Arabidopsis (Arabidopsis thaliana) pollen. A combination of functional genomics, gene expression, in vivo and in(More)