yam8+, a Schizosaccharomyces pombe Gene, Is a Potential Homologue of the Saccharomyces cerevisiae MID1 Gene Encoding a Stretch- Activated Ca2+-Permeable Channel

The Saccharomyces cerevisiae MID1 gene encodes a stretch-activated Ca 2+ -permeable channel. In a protein database, we found a Schizosaccharomyces pombe gene whose predicted protein shows 26% identical and 62% similar to the Mid1 channel in amino acid sequence. cDNA derived from this gene, designated yam8 + , was isolated by reverse transcription-polymerase chain reaction (RT-PCR). Further analysis showed that the Yam8 protein consists of 486 amino acids and has 6 hydrophobic segments. The yam8 + cDNA, placed under the S. cerevisiae TDH3 promoter, partially complemented the mating pheromone-induced death ( mid ) phenotype of the S. cerevisiae mid1 mutant. The expression of the yam8 + cDNA in the mid1 mutant cells partially remediated the mid phenotype and resulted in a slight increase in Ca 2+ uptake activity. These findings suggest that Yam8 is a potential homologue of Mid1.