SCM2, a tryptophan permease in Saccharomyces cerevisiae, is important for cell growth
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SCM2, a novel gene encoding a yeast tryptophan permease, was cloned as a high-copy-number suppressor of cse2-1. The cse2-1 mutation causes cold sensitivity, temperature sensitivity and chromosome missegregation. However, only the cold-sensitive phenotype of cse2-1 cells is suppressed by SCM2 at high copy. SCM2 is located on the left arm of yeast chromosome XV, adjacent to SUP3 and encodes a 65 kDa protein that is highly homologous to known amino acid permeases. Four out of five disrupted scm2 alleles (scm2Δ1-Δ4) cause slow growth, whereas one disrupted allele (scm2Δ5) is lethal. Cells with both the scm2Δ1 and trp1-Δ101 mutations exhibit a synthetic cold-sensitive phenotype and grow much more slowly at the permissive temperature than cells with a single scm2Δ1 or trp1-Δ101 mutation. A region of the predicted SCM2 protein is identical to the partial sequence recently reported for the yeast tryptophan permease TAP2, indicating that SCM2 and TAP2 probably encode the same protein.
Key wordsSaccharomyces cerevisiae Amino acid permeases Transport Tryptophan
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