Acyl-CoA:dihydroxyacetone phosphate acyltransferase in human skin fibroblasts: study of its properties using a new assay method.
In relation to the finding that human skin fibroblasts are capable of de novo either phospholipid biosynthesis, we have studied the properties of acyl-CoA:dihydroxyacetone phosphate acyltransferase in fibroblast homogenates using a new assay method. The results indicate that the acylation of dihydroxyacetone phosphate shows an optimum at pH 5.5 with a broad shoulder of activity up to pH 6.4 and a decline in activity up to pH 8.2. At pH 5.5 the acyltransferase accepts dihydroxyacetone phosphate, but not glycerol 3-phosphate as a substrate. Furthermore, the transferase activity was found to be membrane-bound and inactivated by Triton X-100 at concentrations above 0.025% (w/v). Similar properties have been described for the enzyme as present in rat-liver and guinea-pig liver peroxisomes. These data, together with the finding that acyl-CoA:dihydroxyacetone phosphate acyltransferase is deficient in cultured skin fibroblasts from patients without peroxisomes (Zellweger syndrome), suggest that in cultured skin fibroblasts the enzyme is primarily located in peroxisomes.
D000217:Acyltransferases / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002478:Cells, Cultured; D005347:Fibroblasts / Q000201:enzymology; D006801:Humans; D007700:Kinetics; D011865:Radioisotope Dilution Technique; D012867:Skin / Q000201:enzymology*
D002250:Carbon Radioisotopes; D000217:Acyltransferases; C020051:glycerone-phosphate O-acyltransferase