Fatty acid-binding protein activities in bovine muscle, liver and adipose tissue

Subcutaneous adipose tissue, sternomandibularis muscle and liver were obtained from steers immediately postmortem. Muscle strips and adipose tissue snips were incubated with 0.75 mM [1-14C]palmitate and 5 mM glucose. Muscle strips esterified palmitate at the rate of 2.5 nmol/min per gram tissue, which was 30% of the rate observed for adipose tissue. Fatty acid-binding protein activity was measured in 104,000 x g supernatant fractions of liver, muscle and adipose tissue homogenates. Muscle and adipose tissue fractions bound 840 and 140 pmol [1-14C]palmitoyl-CoA per gram tissue, respectively. Fatty acid-binding protein activity was greater in adipose tissue than in muscle when data were expressed per milligram protein (35 vs. 13 pmol palmitoyl-CoA bound per milligram of soluble protein, respectively). Fatty acid binding-protein activity was correlated with the rate of palmitate esterification within each tissue. Liver contained the highest fatty acid-binding protein activity (13,000 pmol palmitoyl-CoA bound per gram tissue and 215 pmol palmitoyl-CoA bound per milligrams soluble protein).