We have previously shown that system L amino acid transporters are responsible for cellular uptake of S-nitroso-L-cysteine (L-CSNO). In this study we examined the characteristics of L-CSNO uptake in Xenopus oocytes expressing system L transporters and found that uptake increased only when both 4F2 heavy chain (4F2HC) and either LAT1 or LAT2 light chain were co-expressed. The Km for transport was 57 ± 8 µM for 4F2HCAT1 and 520 ± 52 µM for 4F2HCAT2. Vascular endothelial and smooth muscle cells were shown to express transcripts for 4F2HC and for both LAT1 and LAT2. Transport of L-CSNO into red blood cells, endothelial cells and smooth muscle cells was inhibited by BCH and by large neutral amino acids demonstrating functional system L transporters in each cell type. Uptake of L-CSNO led to accumulation of cellular S-nitrosothiols and inhibition of both growth factor-induced ERK phosphorylation and TNF-mediated IB degradation. Similar effects were seen when cells were incubated simultaneously with S-nitrosoalbumin and L-cysteine but not with D-cysteine or with S-nitrosoalbumin alone. In each case, nitrosylation of proteins and cellular responses were blocked by BCH. Together, these data suggest that transmembrane movement of NO equivalents from the plasma albumin NO reservoir requires the activity of 4F2HCAT1 and/or 4F2HCAT2 and that transnitrosylation and transport of L-CNSO are important steps mediating cellular responses to S-nitrosoalbumin.