Publisher Summary This chapter presents detailed analysis of sterols and sterol derivatives of well-characterized (by a rich array of both morphological and biochemical markers) membrane fractions from etiolated maize coleoptiles, with a special focus on a plasma membrane (PM)-rich fraction. Then data about the different cellular sites of plant sterol biosynthesis in the same material are presented. It is presented in the chapter that it is possible to modify the sterol profile of higher plant membranes using sterol biosynthesis inhibitors. Results that have obtained with maize roots treated by fenpropimorph are given. If both free sterols and sterol conjugates of membrane fractions are to be analyzed, then the total lipid must be extracted three times with 6 vol of dichloromethane-methanol (2:1, v/v). To obtain sterols from steryl esters (SE), the corresponding fraction can be hydrolyzed by heating for one hour with 5 ml of 6% (w/v) KOH in methanol and pyrogallol.

[58] Plant membrane sterols: Isolation, identification, and biosynthesis

Publisher Summary This chapter discusses the membrane flow via the Golgi apparatus (GA) of higher plant cells. GA plays a significant role in membrane flow processes, as a large part of the intracellular transport of macromolecules takes place via dictyosomes. Therefore, the membranes of the GA are considered as packing material and transportation vehicles for the transfer of polysaccharides and proteins from their sites of synthesis to the plasma membrane (PM). The transfer processes constitute a membrane flow beginning at the GA or, when starting at the endoplasmic reticulum (ER), via the GA. Membrane transfer from the ER to the PM via the GA can be divided into three different phases. Those three phases are, (1) beginning at the ER and ending at the forming faces of the dictyosomes; (2) comprising the flow through the cisternal stack of the dictyosomes, and (3) extention from the maturing faces of the dictyosomes to the PM. The velocity of granulocrine secretion involves measurements based on the use of content markers; measurements based on membrane markers; and calculations derived from a morphometric analysis of thin sections. The recycling of membrane from the PM is a necessary consequence of granulocrine secretion.

Z.A. Wojciechowski

Papers

Localization of plant UDP-glucose:sterol glucosyltransferase in the Golgi membranes