FIG. 2.

Positive element for lens expression 5′ to the ZPE. (a) The −206 to +70 promoter is active in lens cells but is much less active than the −229 to +70 promoter. The CAT reporter activities of ζ lens promoter constructs transiently transfected in N/N1003A lens cells are shown. Constructs: control, pSV0ATCAT parent plasmid with no promoter; −206, −206/+70.CAT; −229, −229/+70.CAT; −756, −756/+70.CAT. The relative CAT activity, normalized for equal β-galactosidase activity to control for transfection efficiency, is shown. A schematic of the promoter is shown below. (b) EMSA of the −229 to −188 probe with nuclear extracts of rabbit N/N1003A cells (N1003A), extracts of rat lens fiber (Fib) and epithelial (Epi) cells, and nuclear extract of mouse brain (Brain). UB-A and UB-B complexes are indicated by arrows. C, S, and N show results of competition experiments: C, control with no additional competitor; S, self (−229 to −188) competition; N, nonself (−202 to −152) competition.