a large excess of unlabeled l-t3 in the medium blocked influx and efflux of labeled l-t3 , indicating a saturable carrier-mediated transport process across the plasma membrane . the transport obeyed simple michaelis-menten kinetics with an apparent km of 53 nm and a vmax of 4.3 pmol/min.10 ( 8 ) cells at 0 c .
C0007603
plasma membrane
C0007634
cells