Fig. 4. Sys1p is involved in transport of Gas1p. (A) Congo Red hypersensitivity of the sys1 mutant. Different mutant cells (as indicated) were serially diluted and spotted on plates of YPD, Congo Red (100 µg/ml), and Congo Red (100 µg/ml) with sorbitol. A gas1 mutant was used as a control cell. (B) GFP-GPI (Gas1p) distribution is abnormal in arl1- and sys1-mutant cells. GFP-GPI (Gas1p) or Gap1^K9K16-GFP were transformed into wild-type, arl1-, sys1- and arf3-null cells and then induced in selection medium containing 2% galactose for 16 hours. Living cells were imaged using a Zeiss microscope.