title: Characterisation of detergent-insoluble membranes in pollen tubes of Nicotiana tabacum (L.).
abstract: Pollen tubes are the vehicle for sperm cell delivery to the embryo sac during fertilisation of Angiosperms. They provide an intriguing model for unravelling mechanisms of growing to extremes. The asymmetric distribution of lipids and proteins in the pollen tube plasma membrane modulates ion fluxes and actin dynamics and is maintained by a delicate equilibrium between exocytosis and endocytosis. The structural constraints regulating polarised secretion and asymmetric protein distribution on the plasma membrane are mostly unknown. To address this problem, we investigated whether ordered membrane microdomains, namely membrane rafts, might contribute to sperm cell delivery. Detergent insoluble membranes, rich in sterols and sphingolipids, were isolated from tobacco pollen tubes. MALDI TOF/MS analysis revealed that actin, prohibitins and proteins involved in methylation reactions and in phosphoinositide pattern regulation are specifically present in pollen tube detergent insoluble membranes. Tubulins, voltage-dependent anion channels and proteins involved in membrane trafficking and signalling were also present. This paper reports the first evidence of membrane rafts in Angiosperm pollen tubes, opening new perspectives on the coordination of signal transduction, cytoskeleton dynamics and polarised secretion.
authors.affiliation: Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy alessandra.moscatelli@unimi.it.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Moscatelli
authors.affiliation: Laboratorio di Proteomica Funzionale, Dipartimento di Scienze della Vita, Università degli Studi di Siena, Via Aldo Moro 2, 53100 Siena, Italy.
authors.forename: Assunta
authors.initials: A
authors.lastname: Gagliardi
authors.affiliation: Laboratoire de Biogenèse Membranaire, Université Bordeaux Segalen, 71 Avenue Edouard Bourlaux, 33883 Villenave d'Ornon, France.
authors.forename: Lilly
authors.initials: L
authors.lastname: Maneta-Peyret
authors.affiliation: Laboratorio di Proteomica Funzionale, Dipartimento di Scienze della Vita, Università degli Studi di Siena, Via Aldo Moro 2, 53100 Siena, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Bini
authors.affiliation: Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy.
authors.forename: Nadia
authors.initials: N
authors.lastname: Stroppa
authors.affiliation: Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Onelli
authors.affiliation: Laboratorio di Proteomica Funzionale, Dipartimento di Scienze della Vita, Università degli Studi di Siena, Via Aldo Moro 2, 53100 Siena, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Landi
authors.affiliation: Dipartimento di Scienze della Vita, Università degli Studi di Siena, Via P. A. Mattioli 4, 53100 Siena, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Scali
authors.affiliation: Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy Present address: Institute of Biophysics, National Research Council and FBK, 38123 Trento, Italy.
authors.forename: Aurora Irene
authors.initials: AI
authors.lastname: Idilli
authors.affiliation: Laboratoire de Biogenèse Membranaire, Université Bordeaux Segalen, 71 Avenue Edouard Bourlaux, 33883 Villenave d'Ornon, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Moreau
keywords: Membrane microdomains; Nicotiana tabacum (L.); Pollen tube