Sphingoid long chain bases have many effects on cells including inhibition or stimulation of
growth. The physiological significance of these effects is unknown in most cases. To begin to
understand how these compounds inhibit growth, we have studied Saccharomyces
cerevisiae cells. Growth of tryptophan (Trp−) auxotrophs was more strongly inhibited by
phytosphingosine (PHS) than was growth of Trp+ strains, suggesting that PHS diminishes
tryptophan uptake and starves cells for this amino acid. This hypothesis is supported by data …