Identification of an alternatively spliced form of the Tat Interactive Protein (Tip60), Tip60(beta)

Tip60 was originally isolated as a Tat interactive protein. It was subseque ntly shown that Tip60 had histone acetyltransferase (HAT) activity. In stud ies to understand gene-expression regulation that might involve HAT activit y, we PCR-amplified Tip60 from a human heart marathon-ready cDNA library. A s a result, we identified an alternatively spliced form of Tip60, Tip60 bet a (we refer to the previously cloned Tip60 as Tip60 alpha). Tip60 beta cDNA is slightly smaller than Tip60 alpha, and sequencing indicates that there is a deletion of 156 bp in the coding region of the gene. The predicted Tip 60 beta protein therefore lacks 52 amino acids when compared with Tip60 alp ha. The Tip60 alpha. gene is encoded by 14 exons, and Tip60 beta is an alte rnatively spliced form resulting from the exclusion of exon 5 during the sp licing process. Exon 5 encodes a proline-rich region that is known to be im portant for protein-protein interaction. Tip60 beta is expressed in a varie ty of human tissues and cell lines, and the protein is present in both the nucleus and cytoplasm in contrast to Tip60 alpha, which is entirely nuclear . The results suggest that Tip60 beta may have functions additional to thos e of Tip60 alpha in cells and tissues. (C) 2000 Elsevier Science B.V. All r ights reserved.