Calcium dependent protein phosphorylation in germinated pollen of nicotiana alata an ornamental tobacco

Polya, G.M.; Micucci, V.; Rae, A.L.; Harris, P.J.; Clarke, A.E.

Physiologia Plantarum 67(2): 151-158


ISSN/ISBN: 0031-9317
Accession: 004867756

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The 40000 g supernatant and 40000 g pellet from extracts of germinated pollen of Nicotiana alata Link et Otto contain protein kinase activity which catalyzes the phosphorylation of histones, casein and a range of endogenous polypeptides. Phosphorylation of certain low-molecular-weight, casein-derived polypeptides is activated at low (12-37 .mu.M) and partially inhibited at higher (540 .mu.M) concentration of free Ca2+. Histone phosphorylation is largely Ca2+-dependent and is activated by 540 .mu.M free Ca2+. No activation of protein phosphorylation by micromolar concentrations of calmodulin is found, but phenothiazine-derived calmodulin antagonists markedly stimulate protein phosphorylation.