Genomic organization and mRNA processing of theCCR3 gene.

A schematic diagram of the organization of the CCR3 gene is shown. The translated DNA area is depicted as an open rectangle and untranslated DNA is shown as shaded rectangles. Restriction enzymes are labeled as follows: E, EcoRI; G, BglII; B,BamHI; and H, HindIII. Exons are labeled as E1 through E4; introns as I1 through I3. The precise position of exon 2 has not been determined and this is indicated by the pair of slashed lines. DNA fragments flanked by single asterisk (*) and double asterisk (**) were fully sequenced (Genbank accession numbers AF237380,AF237381, and U51241) and the BglII sequence is shown in Figure 4. Primers used for long-range PCR are labeled as F and R flanking the ∼17 kb PCR product. Below are the corresponding mRNA species: A, majority of mRNA species contain only exons 1 and 4; B and C show usage of exon 1 with exons 2 or 3, respectively.