The AF-1-deficient estrogen receptor ERα46 isoform is frequently expressed in human breast tumors

Breast Cancer Research

Table 1 Proteomic analysis of the 46-kDa protein detected in tumor samples

Tumor	Sample	Mascot score	Cov. (%)/isoform	No. of identified peptides	First N-terminal peptide identified and validated	Peptide identified before Met 174	Last C-terminal peptide identified and validated
MCF7	IP46	759	23.3	14	212–231	No	556–581
MCF7	IP66	440	24.4	12	009–032	Yes	556–581
Tumor 1	IP46	96	8.0	5	402–412	No	556–581
Tumor 1	IP66	52	4.4	1	556–581	No	556–581
Tumor 2	IP 46	228	15.3	5	184–206	No	556–581
Tumor 2	IP 66	522	25.0	10	38–48	Yes	556–581
Tumor 3	IP 46	65	3.0	1	450–467	No	450–467
Tumor 4	IP 46	35	1.8	1	402–412	No	402–412

Proteomic analysis results from the different cell lines and the four breast tumor samples
The % of sequence coverage corresponds to the number of amino acid residues identified in the proteomic analysis divided by the total number of amino acid residues in the protein sequence. The Mascot score is described in [52]. It uses statistical methods to assess the validity of a match. This enables a simple rule to be used to judge whether a result is significant or not. We report scores as -10*LOG10(P), where P is the absolute probability. A probability of 10^-20 thus becomes a score of 200

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