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The polyamine (PA) content and the transglutaminase (TGase) activity have been investigated in Pyrus communis pollination with compatible and self-incompatible (SI) pollen in order to deepen their possible involvement in the progamic phase of plant reproduction. The PA distribution as free, perchloric acid (PCA)-soluble and PCA-insoluble fractions in(More)
A transglutaminase (TGase; EC activity, which shared many properties with the TGase activity of the Helianthus tuberosus chloroplast, was observed in the Zea mays L. chloroplast and in its fractions. This activity was found to be prevalent in thylakoids; bis-(glutamyl) spermidine and bis-(glutamyl) putrescine were the main polyamine conjugates(More)
An extracellular form of the calcium-dependent protein-cross-linking enzyme TGase (transglutaminase) was demonstrated to be involved in the apical growth of Malus domestica pollen tube. Apple pollen TGase and its substrates were co-localized within aggregates on the pollen tube surface, as determined by indirect immunofluorescence staining and the in situ(More)
Aliphatic polyamines (PAs) are involved in the delay or prevention of plant senescence, but the molecular mechanism is not clarified. The hypothesis is put forward that one of the mechanisms by which PAs modulate leaf senescence and chlorophyll stabilisation could be due to their modification of chlorophyll-bound proteins, catalysed by transglutaminase(More)
Corolla life span of undetached flowers of Nicotiana tabacum was divided into stages from the closed corolla (stage 1) through anthesis (stage 5) to death (stage 9). Senescence began around stage 6 in the proximal part, concomitantly with DNA laddering. Nuclear blebbing, DNA laddering, cell wall modification, decline in protein, water, pigment content and(More)
The activity of transglutaminase (TGase), an enzyme responsible for polyamine conjugation to proteins, was analyzed in relationship to developmental cell death (DCD) during the flower life span stages of the tobacco (Nicotiana tabacum) corolla. As the DCD exhibits an acropetal gradient, TGase was studied in corolla proximal, medial, and distal parts. TGase(More)
Transglutaminases (TGases) are ubiquitous enzymes that take part in a variety of cellular functions. In the pollen tube, cytoplasmic TGases are likely to be involved in the incorporation of primary amines at selected peptide-bound glutamine residues of cytosolic proteins (including actin and tubulin), while cell wall-associated TGases are believed to(More)
The transglutaminase (TGase) is present in the pollen tube where it most likely participates in the regulation of different activities including the organization of cytoskeletal elements (microtubules and actin filaments). In addition to a cytosolic form of TGase, new data suggest the existence of TGase forms associated with the internal membranes and with(More)
The light stimulation of transglutaminase (TGase EC activity was verified by incubating isolated chloroplasts of Helianthus tuberosus L. continuously or for alternate periods of light or dark (light/dark and dark/light). The first 10 min of incubation always represented the critical period. Light-harvesting complexes of photosystem II (LHCII) were(More)
Incubation of chloroplasts of Helianthus tuberosus with labelled putrescine and/or spermidine and proteolytic digestion of their trichloroacetate-soluble and -insoluble proteins revealed the presence of N-(gamma-glutamyl)-putrescine, N1,N4-bis-(gamma-glutamyl)-putrescine and N1,N8-bis-(gamma-glutamyl)spermidine. This finding may be regarded as unequivocal(More)