TABLE 3.

Inhibition of YhcL-dependent l-[¹⁴C]cystine uptake in the presence of different compounds

Competitora	% Inhibiton
l-Cystine	92 ± 3
Seleno-dl-cystine	67 ± 4
l-Leucine	48 ± 6
l-Valine	43 ± 2
l-Alanine	42 ± 7
S-Methyl-l-cysteine	40 ± 1
l-Cysteine	38 ± 1
l-Djenkolic acid	20 ± 1
dl-Cystathionine	19 ± 1
l-Methionine	19 ± 1
dl-Homocystine	18 ± 2
dl-Homocysteine	<10
Oxidized glutathione	<10
Reduced glutathione	<10

^al-[¹⁴C]cystine was used at a concentration of 5 μM, and the unlabeled amino acids or sulfur compounds were present at a concentration of 50 μM. The initial l-[¹⁴C]cystine uptake rate was measured.