The CYSTM (cysteine-rich transmembrane module) protein family comprises small molecular cysteine-rich tail-anchored membrane proteins found in many eukaryotes. The Saccharomyces cerevisiae strains carrying the CYSTM genes YDRO34W-B and YBR056W-A (MNC1) fused with GFP were used to test expression of these genes under different stresses. The YBR056W-A (MNC1) and YDR034W-B genes are expressed under stress conditions caused by the toxic concentrations of heavy metal ions such as manganese, cobalt, nickel, zinc, cuprum, and 2.4-dinitrophenol uncoupler. YDR034W-B but not YBR056W-A is expressed under alkali and cadmium stresses. YBR056W-A is localized in intracellular membranes, while YDR034W-B is localized in the cytoplasmic membrane. The null-mutants in both genes demonstrated both decreased cell concentration and lytic phenotype when cultivated in the presence of excess manganese. This indicates the involvement of Mnc1 and YDR034W-B proteins in manganese detoxification, probably by complexation of its ion.