Probing the membrane topology of a diacylglycerol acytransferase type I from Brassica Napus

Diacylglycerol acyltransferase (DGAT), an integral membrane protein of the endoplasmic reticulum, catalyses the final step in the sn-glycerol-3-phosphate pathway leading to triacylglycerol. Although DGAT has been cloned from a variety of species, including the major oilseed crop of Canada, canola (Brassica napus), little is known about the structure/function of the enzyme. BnDGAT1 is the major isoform of type I DGAT (DGAT-I) in microspore-derived cell suspension cultures of B. napus L. cv Jet Neuf, with the possible existence of a truncated form of BnDGAT1 known as BnDGAT2. In order to gain some insight into the topology of the enzyme, type I DGAT from B. napus was investigated using two approaches: (1) in vitro translation in the presence of microsomes and (2) immunochemical analyses of microsomes isolated from cell suspension cultures, both in combination with proteolytic mapping. Difficulties were encountered with the in vitro translation approach, possibly due to proper incorporation of the polypeptide into microsomal vesicles. Two cytocolic regions were identified in BnDGAT1, and one cytosolic region in putative BnDGAT2, using the immunochemical approach, thus providing some insight into the topology of B. napus DGAT-I. The results here support and nine and eight membrane-spanning topology for BnDGAT1 and BnGAT2, respectively.

Authors

• Foroud, Nora Afsaneh
• University of Lethbridge. Faculty of Arts and Science

• Dissertations, Academic
• Membrane proteins
• Diglycerides
• Acyltransferases
• Oilseed plants
• Rape (Plant) -- Research

Identifier

hdl:10133/256

OAI identifier oai:identifier

oai:opus.uleth.ca:10133/256