High-affinity pH-dependent nicotinamide riboside transporter which also transports thiamine with low affinity. Involved in 5-fluorocytosine sensitivity. Optimum pH is 3.5-6.5. Expression is controlled by the transcription repressors SUM1, HST1 and RFM1. Belongs to the purine-cytosine permease (2.A.39) family.