Membrane function in cystic fibrosis. II. Methionine transport in normal and cystic fibrosis fibroblasts.

Initial rate kinetics of methionine transport, time course of accumulation of methionine, 
and efflux of accumulated methionine were studied in three normal and 
four CF human diploid fibroblast strains. The range of apparent Km's 
was 12.7-32.1 micrometer for the CF strains and 18.3-39.2 micrometer for 
the normal strains. The range of apparent Vmax's was 6.69-9.22 nmole 
mg-1 min-1 for the CF strains and 5.59-7.87 nmole mg-1 min-1 
for the normal strains. The patterns of accumulation and efflux are 
quite similar in all the strains studied except for WI-38, which 
showed somewhat higher efflux and lower accumulation than for others. There 
was no significant difference in the kinetic parameters of methionine transport 
between CF and normal skin fibroblasts, and methionine transport will not 
serve as a marker for cystic fibrosis in cultured fibroblasts. 