The subcellular distribution of acyl CoA: Dihydroxyacetone phosphate acyl transferase in guinea pig liver

Abstract

Summarv: Upon differential centrifugation, the enzyme acyl CoA:dihydroxyacetone phosphate acyl transferase (EC 2.3.1.42) in guinea pig liver is shown to sediment in a lysosomal-peroxisomal fraction. Comparison of the distribution of the marker enzymes and of DHAP acyl transferase indicates that the acyl transferase is localized in peroxisomes (microbodies). Acyl dihydroxyacetone phosphate (acyl DHAPl) has been shown to be an important intermediate in the biosynthesis of glycerolipids containing ester and ether bonds (1,2). This lipid is formed by a direct acylation of DHAP with a long chain acyl CoA, and this acyl transferase (EC 2.3.1.42) has been shown to be widely distributed in both the mitochondrial and microsomal fractions of different mammalian tissues (2-6). The activity of this enzyme is very high in guinea pig liver, (3) and the acyl transferase has been solubilized and partially purified from this organ (7). During this work the distribution of this acyl transferase in different subcellular fractions of guinea pig liver was rigorously investigated, and it was found that this enzyme was highly enriched in a particulate fraction which contained mainly lysosomes and peroxisomes. These results are presented here.

Evidence for the existence of isoenzymes of glycerol phosphate acyltransferase

“…Taken with the heatinactivation studies, the present results thus constitute convincing evidence that the mitochondrial and microsomal glycerol phosphate acyltransferases are chemically distinct. Glycerolipid synthesis can also occur via the acylation of dihydroxyacetone phosphate (see the introduction). It has recently been shown that a dihydroxyacetone phosphate acyltransferase is located in the peroxisomes, distinct from either of the glycerol phosphate acyltransferases (Jones & Hajra, 1977). This does not, of course, imply that the enzymes studied here cannot use dihydroxyacetone phosphate as a substrate.…”

“…The biosynthesis of phosphatidate from sn-glycerol 3phosphate involves two distinct enzymes, glycerol phosphate acyltransferase (acyl-CoA-sn-glycerol 3-phosphate O-acyltransferase, EC 2.3.1.15) and I-acylglycerol phosphate acyltransferase (Yamashita & Numa, 1972). Some early disputes as to the subcellular location of glycerol phosphate acyltransferase in liver have now been resolved, and it is generally agreed that the enzyme is located in both the mitochondria and the microsomal fraction (Stoffel & Schiefer, 1968;Shepard & Hubscher, 1969;Daae & Bremer, 1970;Monroy et al, 1972;Davidson & Stanacev, 1974;Jones & Hajra, 1977). The mitochondrial activity is located in the outer membranes Vol.…”

Peroxisomes: A Nexus for Lipid Metabolism and Cellular Signaling

“…In 1977, Amiya Hajra and colleagues discovered that dihydroxyacetone phosphate acyltransferase (DHAPAT), an enzyme required for the synthesis of acyl DHAP, a precursor for glycerol ether lipids, was localized to peroxisomes (Jones and Hajra, 1977). This was a surprising discovery because it suggested that peroxisomes were not only involved in catabolic reactions, but also the synthesis of phospholipids.…”

Fatty acid specificities of microsomal acyltransferase esterifying positions-1 and −2 of acylglycerols in mammary glands from lactating rats

“…Table 3 presents the fatty acid specificities of the acyltransferases involved in the esterification of the positions-I and -2 of the glycerol. Schlossman & Bell (1976, 1977 (Bjerve et al, 1976;Haldar et al, 1979) and one localized in the peroxisomes and specific for dihydroxyacetone phosphate (Jones & Hajra, 1977). The kinetic data coupled with the relatively high forces used to pellet the mitochondria (225 000g., -min) suggest that any contamination of our microsomal samples by either of these activities is likely to be minimal.…”