Fluorescent staining with PNA and MAA lectins of CHO, Lec2, and complemented Lec2 cells with the 2 patient alleles. (A) All cells are MAA^– and PNA⁺ in the Lec2 cell line (expression of nonsialylated precursor). Unlike this, the opposite phenotype is seen with the parental CHO cell line, where all cells are MAA⁺ and PNA^– (expression of α2,3-sialylated epitope). (B) Complementation of Lec2 with wild-type CMP–sialic acid transporter gene and lack of complementation with either of the A1 or A2 patient's cDNA alleles. The transduction efficiency was of about 50% as illustrated by the MAA-FITC staining of half of the cells transduced with the normal human wild-type transcript. Left, fluorescein-labeled MAA; right, rhodamine-labeled PNA; middle, superimposition of the green and red pictures. A complete change of phenotype (from MAA–, PNA⁺ to MAA⁺, PNA^–) can be seen in the transducted cells.