Active transport of exogenous S-adenosylmethionine and related compounds into cells and vacuoles of Saccharomyces cerevisiae.

Saccharomyces cerevisiae 4094-B (alpha, ade-2, ura-1) in potassium phosphate buffer with glucose under aerobic conditions took up (-)S-adenosyl-l-methionine from the medium in sufficient quantity to permit the demonstration of its accumulation in the vacuole by ultraviolet micrography. The same result was obtained with (+/-)S-adenosyl-l-methionine, (+/-)S-adenosyl-d-methionine, and (-)S-adenosyl-l-ethionine. The rate of uptake was slow with (-)S-adenosyl-S(n-propyl)-l-homocysteine and S-adenosyl-d-homocysteine. S-Adenosyl-l-homocysteine was assimilated rapidly, but intracellular degradation precluded accumulation and ultraviolet micrographic studies. The uptake of 5'-methyl-, 5'-ethyl-, 5'-n-propylthioadenosine, and 5'-dimethylsulfonium adenosine was minimal.