Iodothyronine Interactions with the System L1 Amino Acid Exchanger in 3T3-L1 Adipocytes

Figure 3

Saturable phenylalanine uptake into 3T3-L1 adipocytes. Uptake of [³H]phenylalanine over 3 minutes at 5 different phenylalanine concentrations as indicated (between 1 $\mu$M and 500 $\mu$M) was measured. Values are shown $\pm$ SEM for 3 measurements in a representative experiment and are expressed with the nonsaturable component of uptake removed. Figure inset shows a Lineweaver-Burk plot relating [³H]-phenylalanine uptake (corrected for nonsaturable component) against external phenylalanine concentration. The overall data provide estimated $K_m$ of 31 $\mu$M and $V_{\max \hspace{0.17em}}$ of 2.6 $\pm$ 0.5 nmol$·$mg protein^-1$·$min^-1 (mean $\pm$sem, $n=6$).