Zonal rotor study of the subcellular distribution of acyl-CoA synthetases, carnitine acyl transferases and phosphatidate phosphatase in the guinea-pig small intestine.

Abstract

Homogenates made from the mucosa of the guinea pig small intestine were fractionated in a zonal rotor by rate and isopycnic centrifugation in sucrose gradients. Density perturbation of endoplasmic reticulum vesicles was done by treating homogenate with pyrophosphate and was analysed by isopyenic centrifugation. Subcellular fractions were analysed for the distribution of markers for brush borders. basolateral plasma membrane. Iysosomes. peroxi. somes. mitochondria. nuclei and endoplasmic reliculum. Fractions werc also analysed for the distribution ofpropionyl-. butyryl-. and palmityl. CoA synthetases. for carnitine acetyl and palmityltransferases. and for phosphatidate phosphatase. Comparison of marker and unknown distributions shows that palmityl- CoA synthetase is located on the endoplasmic reticulum. while propionyl- and butyryl-CoA synthetases and carnitine acetyl and pal. mit)'l transferases are exclusively mitochondrial. I'hosphatidate phosphatase has complex subcellular localisation with activity in brush borders. microsomes (possibly not the endoplasmic reticulum component) and possibly Iysosomes.