Complementation of growth on EGTA by pECA1 is accompanied by expression of the ECA1 polypeptide in pmr1 and pmr1 pmc1 cnb1 mutants. Wild-type yeast (W303), pmr1 (AA542), and pmr1 pmc1 cnb1 (K616) were transformed with control vector (p426) or pECA1 as in Fig. 2. (A) The cells were streaked on SC-URA plates containing galactose and 10 mM EGTA at pH 6.2 and incubated for 3 days at 30°C. (B) To detect the ECA1 polypeptide, microsomal membranes were isolated from pmr1 and pmr1 pmc1 cnb1 mutants transformed with p426 alone (lanes 3 and 5) or pECA1 (lanes 2 and 4). Protein (5 μg) was separated by SDS/PAGE, blotted, and immunostained with antibody against ECA1p (1:50,000). Lane 1 was loaded with microsomal membranes isolated from Arabidopsis (1:500).