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Factors enhancing diacylglycerol acyltransferase activity in microsomes from cell‐suspension cultures of oilseed rape
Author(s) -
Byers Susan D.,
Laroche André,
Smith Kevin C.,
Weselake Randall J.
Publication year - 1999
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-999-0465-6
Subject(s) - microsome , diacylglycerol kinase , biochemistry , chemistry , clinical chemistry , enzyme , cytosol , protein kinase c
Several factors, including an unidentified endogenous component, were found to stimulate microsomal diacylglycerol acyltransferase (DGAT, EC 2.3.1.20) from a microspore‐derived cell‐suspension culture of oilseed rape ( Brassica napus L. cv. Jet Neuf). At a concentration of 25mM, MgSO 4 and MgCl 2 stimulated microsomal DGAT 25‐ and 10‐fold, respectively. AIP and CoA at concentrations of 2 and 1 mM stimulated the enzyme 2.4‐ and 12‐fold, respectively, although the effects were lessened in the presence of higher Mg 2+ concentrations. Although microsomal DGAT activity was increased only slightly by the addition of exogenous sn ‐1,2‐diacylglycerol to the reaction mixture, it was increased substantially by the addition of exogenous phosphatidate. sn ‐Glycerol‐3‐phosphate and other phospholipids tested did not have this stimulatory effect. DGAT activity did not decrease when microsomes were incubated with ATP in the presence of the cytosolic fraction. This fraction, however, contained a small organic compound(s) that stimulated microsomal DGAT activity.