MODULATION OF GTP-DEPENDENT FUSION BY LINOLEIC AND ARACHIDONIC-ACID IN DERIVATIVES OF ROUGH ENDOPLASMIC-RETICULUM FROM RAT-LIVER

The effect of modulation of the content of unsaturated free fatty acid s on GTP-dependent fusion of stripped rough microsomes from rat liver was determined. Cytidine monophosphate, CDP and CTP were all observed to be able to stimulate free fatty acid accumulation and coincident me mbrane fusion. GTP was required for membrane fusion in the presence of cytidine nucleotide but was not required for free fatty acid accumula tion. In the presence of GTP and cytidine nucleotide, the addition of ATP and CoA led to the synthesis of triacylglycerol and marked inhibit ion of both free fatty acid accumulation and membrane fusion. Delipida ted bovine serum albumin also inhibited both free fatty acid accumulat ion and membrane fusion. Analysis by gas chromatography indicated that linoleic acid and arachidonic acid were the most actively fluctuating of the accumulated free fatty acids. Comparison by quantitation indic ated a high correlation between GTP-dependent membrane fusion and chan ges in amount of unesterified linoleic acid and arachidonic acid. The results suggest that polyunsaturated free fatty acids may be required for GTP-dependent membrane fusion.