9.B.316.  The DUF3533 or Nitrosoguanidine Resistance (NGR) Family 

Grey et al. 1995 have molecularly characterized the SNG1 gene that confers hyper-resistance to the mutagen N-methyl-N'nitro-N-nitrosoguanidine (MNNG) in Saccharomyces cerevisiae when overexpressed on a multi-copy plasmid. This hyper-resistance to MNNG is not due to depletion of glutathione pools since multi-copy SNG1 containing yeast transformants contain at least wild type levels of glutathione; DNA repair seems unaffected in these transformants as the multi-copy SNG1-mediated MNNG hyper-resistance is also seen in DNA repair mutants belonging to each of the three epistasis groups of yeast repair mutants. SNG1 is not under control of the YAP1 encoded transcription activator that controls expression of at least two genes involved in MNNG metabolism in yeast. sng1 null mutants are viable but exhibit only slight sensitivity to MNNG, indicating that SNG1 does not encode a protein involved in a major detoxification step of this mutagen. SNG1 encodes a 547 aa protein containing seven TMSs.



Grey, M., C.T. Pich, E. Haase, and M. Brendel. (1995). SNG1--a new gene involved in nitrosoguanidine resistance in Saccharomyces cerevisiae. Mutat Res 346: 207-214.


TC#NameOrganismal TypeExample

The nitrosoguanidine resistance protein of 547 aas and 6 or 7 TMSs, SNG1.  May function as a N-methyl-N'nitro-N-nitrosoguanidine (MNNG) export permease (Grey et al. 1995).

SNG1 of Saccharomyces cerevisiae


Putative nitrosoguanidine resistance protein, SNG1, of 594 aas and 6 TMSs in a 1 + 5 TMS arrangement.

SNG1 of Phialophora attae


Uncharacterized protein of 734 aas and 6 TMSs in a 1 + 4 + 1 TMS arrangement.

UP of Kwoniella heveanensis


Uncharacterized protein of 617 aas and 6 TMSs in a 1 + 4 + 1 TMS arrangement.

UP of Fomitiporia mediterranea