9.A.23 The Niacin/Nicotinamide Transporter (NNT) Family NiaY (BH3254) of Bacillus halodurans C-125 is a putative niacin (vitamin B3 or nicotinic acid)/nicotinamide transporter (Rodionov et al., 2009). The protein has eight predicted TMSs and is homologous to the PTS Enzyme IIC components of the glucose/fructose families (4e^-7). In addition, similarity was observed for TMSs 1-6 with TMSs 7-12 of an MFS transporters (2.A.1.35.2; RosA; 6e^-4). In spite of the sequence similarity with PTS permeases, this protein is placed in a new family (9.A.23) because of its dissimilar predicted function and PTS-independent mechanism of action. The generalized reaction predicted for NiaY is: niacin and/or nicotinamide (out) ⇌ niacin and/or nicotinamide (in)
References:
Rodionov, D.A., P. Hebbeln, A. Eudes, J. ter Beek, I.A. Rodionova, G.B. Erkens, D.J. Slotboom, M.S. Gelfand, A.L. Osterman, A.D. Hanson, and T. Eitinger. (2009). A novel class of modular transporters for vitamins in prokaryotes. J. Bacteriol. 191: 42-51.
Rodionov, D.A., X. Li, I.A. Rodionova, C. Yang, L. Sorci, E. Dervyn, D. Martynowski, H. Zhang, M.S. Gelfand, and A.L. Osterman. (2008). Transcriptional regulation of NAD metabolism in bacteria: genomic reconstruction of NiaR (YrxA) regulon. Nucleic Acids Res 36: 2032-2046.
Examples:
TC#	Name	Organismal Type	Example
9.A.23.1.1	*The putative niacin/nicotinamide transporter, NiaY (Rodionov et al.* 2008)**	Bacteria	*NiaY of Bacillus halodurans* (Q9K7V5)**

9.A.23.1.2	Uncharacterized protein of 390 aas and 11 TMSs. Its gene maps adjacent to and in the same operon with a nicotinate phosphoribosyl transferase gene and a MATE family (TC# 2.A.66) exporter gene.	Tennericutes	UP of Acholeplasma laidlawii