Escherichia coli is known to contain more than one active transport system for nucleoside uptake. In the present study we report the sequence of a gene encoding a second nucleoside transport system, nupC (in addition to nupG). An open reading frame (ORF) of 1200 bp was identified that codes for a hydrophobic polypeptide of 43,560 Da and an NupC fusion protein was shown to be membrane associated. The native NupC protein is also identified, following over-expression. NupC exhibits short regions of homology to several membrane-associated proteins, including LacY and Cyd. Analysis of the nupC promoter region revealed the presence of at least two putative CRP-binding sites, centred at -40bp and -89bp, which probably flank a CytR-binding site. In addition, an adjacent IS 186 element was identified and found to reside within a putative terminator structure, downstream from the nupC ORF. This arrangement is shown to reflect the previously established gene order on the E. coli chromosome.