title: Heterogeneity of auxin-accumulating membrane vesicles from Cucurbita and Zea: a possible reflection of cell polarity.
abstract: When microsomes from hypocotyls of Cucurbita pepo L. or coleoptiles of Zea mays L. were centrifuged on dextran-sucrose gradients a heterogeneity of auxin-accumulating vesicles was observed. Vesicles from the top part of the gradient showed saturable, specific accumulation of indole-3-acetic acid with only a small stimulation by phytotropins, and with very few binding sites for 1-N-naphthylphthalamic acid. In the vesicles from the lower part of the gradient, net accumulation of indole-3-acetic acid could be strongly increased by addition of phytotropins; binding of 1-N-naphthylphthalamic acid was high in this region. After two-phase partitioning, both kinds of vesicles were found in the upper-phase membrane fraction considered to be purified plasma membrane. The hypothesis is discussed that vesicles can be separated from the apical and basal parts of the cell's plasmalemma.
authors.affiliation: Institut für Biologie III der Universität, Schänzlestrasse 1, D-7800, Freiburg i.Br., Federal Republic of Germany.
authors.forename: M
authors.initials: M
authors.lastname: Lützelschwab
authors.forename: H
authors.initials: H
authors.lastname: Asard
authors.forename: U
authors.initials: U
authors.lastname: Ingold
authors.forename: R
authors.initials: R
authors.lastname: Hertel