Genomic organization of the STAT5 locus as revealed by fiber-FISH

Veterinarni Medicina 45, 2000, 281-284

The STAT-transcription factors form a family of signal transducers and activators of transcription mediating the action of a variety of peptide hormones and cytokines via the Janus-type kinases. At least seven distinct STAT-encoding genes have been identified, STAT1-6. STAT5 being encoded by two genes, known as STAT5A and STAT5B. STAT factors arose from a common ancesteral gene by repeated gene duplication events. We had detected many copies of pseudogenes (9 from among 14 isolates) during isolation of the bovine genes. Since our previous gene mappings had shown that both genes must be located in close vicinity on BTA19 we used fiber FISH to verify true overlap of new isolates with proven STAT5A or B gene isolates. However, extended areas (several kbp) of the isolates revealed identical restriction maps and sequences with previously identified authentic gene isolates, but grossly diverging restriction maps in other segements. Therefore, the results of restriction mapping were proven by an independent technique, the DNA-fiber-FISH hybridizations. Indeed, the STAT5B-encoding gene resides only about 40 kbp downstream of the STAT5A-encoding gene in correspondence to restriction mapping. While it is clear that the STAT5B gene is located 3' from the STAT5A gene, the 5'-3'orientation of the STAT5B-encoding is unclear, since we did not determine the relative position of the 5'-region of the latter gene. Thus, while the entire locus comprises about 85 kbp as revealed by these hybridizations, it might be a little larger

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