Fig. 1. Cytoplasmic domain amino acid sequences for full-length and 15-containing isoforms of PECAM-1. (A) Illustration of the cDNA and predicted amino acid sequences for the terminal cytoplasmic tail regions of the PECAM-1 splice variants described in this study. The new C-terminus created by deletion of exon 15 is boxed, and dotted lines indicate splice junctions. Stop codons are also indicated. A schematic diagram of the full-length (filled circles) and alternatively spliced 15-containing PECAM-1 cytoplasmic domains (unfilled circles) is shown in (B). Phylogenetically conserved tyrosine residues are colored yellow, whereas conserved serine residues are colored orange. Note that the 15 form is missing two serine residues and one tyrosine residue and has a novel six-amino-acid C-terminal sequence. (C) A rabbit polyclonal antibody produced against the novel 15 PECAM-1 C-terminal region reacts with human 15 PECAM-1, but not full-length WT PECAM-1, in HEK293 cells transfected with specific cDNAs encoding these isoforms. Fig. 1A,B are adapted, with permission, from Newman and Newman (Newman and Newman, 2003).