Schematic representation of 4.1R, CO.1, CO.2, and 4.1G in their C-terminal regions.

(A) Abnormal splicing events generated at 4.1R pre-mRNA from exon 20 mutation, and leading to the spliceoforms encoding CO.1 and CO.2. (B) Amino acid sequence alignment of normal 4.1R, CO.1, and CO.2. Peptide epitopes for specific antibodies AbCO and AbCT are highlighted in black boxes. (C) Sequence alignment of 4.1R and 4.1G CTDs. Note the high degree of amino acid identity between the 2 proteins at 4.1R exons 20–encoded (shaded) and 21–encoded (boxed) sequence.