Table 2. Single molecule analysis of PTB target sites on FAS RNA.

RNA	Number of PTB target sites			Fraction of RNA with bound PTB-GFP, %
	A	B	C
wt FAS	3–4	3–4.5	3–4	2.6
m0 mutant	3	2–4	3	2.9
Tpm 1 RNA	5–6	6.5	6	7.9

(A) the number of the target sites was estimated by fitting distribution of bleaching steps by the truncated binomial distribution; (B) the number of the target sites was estimated by linear fit of iPi/P(i−1) values; (C) the number of the target sites was estimated from the analysis of total emissions (see Materials and Methods). The data in the last column were obtained at 1:20 dilution of PTB-GFP overexpressesing nuclear extract.