A density gradient method is used to isolate membrane vesicles from brown adipose tissue. These respond to changes in osmolarity and show the classical overshoot pattern when L-alanine uptake is assayed. Transport is shown to be effected by two components: a linear (Kd=0.498 min−1) and Na+-dependent saturable component (Km=2.3 mM) and a Vmax=19.9 pmol/μg protein·min). This pattern is similar to that shown by cells isolated from brown adipose tissue.
Abbreviations MeAIB, Methyl-aminoisobutyric acid