title: Co-localization of putative calcium channels (phenylalkylamine-binding sites) on oil bodies in protoplasts from dark-grown sunflower seedling cotyledons.
abstract: Oil bodies are spherical entities containing a triacylglycerol (TAG) matrix encased by a phospholipid monolayer, which is stabilized by oil body-specific proteins, principally oleosins. Biochemical investigations in the recent past have also demonstrated the expression of calcium-binding proteins, called caleosins, as a component of oil body membranes during seed germination. Using DM-Bodipy-phenylalkylamine (PAA; a fluorescent derivative of phenylalkylamine)-a fluorescent probe known to bind L-type calcium channel proteins, present investigations provide the first report on the localization and preferential accumulation of putative calcium channel proteins on/around oil bodies during peak lipolytic phase in protoplasts derived from dark-grown sunflower (Helianthus annuus L. cv Morden) seedling cotyledons. Specificity of DM-Bodipy-PAA labeling was confirmed by using bepridil, a non-fluorescent competitor of PAA while non-specific dye accumulation has been ruled out by using Bodipy-FL as control. Co-localization of fluorescence from DM-Bodipy-PAA binding sites (ex: 504 nm; em: 511 nm) and nile red fluorescing oil bodies (ex: 552 nm; em: 636 nm) has been undertaken by epifluorescence and confocal laser scanning microscopy (CLSM). It revealed the affinity of PAA-sensitive ion channels for the oil body surface. Findings from the current investigations highlight the significance of calcium and calcium channel proteins during oil body mobilization in sunflower.
authors.affiliation: Department of Botany, Gargi College, University of Delhi, New Delhi, India.
authors.forename: Shweta
authors.initials: S
authors.lastname: Vandana
authors.forename: Satish C
authors.initials: SC
authors.lastname: Bhatla
mesh_terms: D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D018548:Cotyledon / Q000378:metabolism; D006368:Helianthus / Q000378:metabolism*; D008066:Lipolysis; D009570:Nitriles; D010627:Phenethylamines; D010938:Plant Oils / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism*; D011523:Protoplasts / Q000378:metabolism
chemical_list: D020746:Calcium Channels, L-Type; D009570:Nitriles; D010627:Phenethylamines; D010938:Plant Oils; D010940:Plant Proteins; C072556:5-(3-(3-(4,4-difluoro-5,7-dimethyl-3,4-diaza-4-bora-indacen-3-yl)propionamido)phenethyl-N-methylamino)-2-isopropyl-2-(3,4,5-trimethoxyphenyl)valeronitrile; D002118:Calcium