An additional exon of stress-inducible heat shock protein 70 gene (HSP70-1).

The HSP70-1 gene, reportedly a single exon, encodes a major stress-inducible 72-kDa heat shock protein (HSP70). We recently demonstrated that patients with major depression had a 162-base pair (bp)-deletion in the 5'-flanking sequence of HSP70-1 mRNA in their peripheral blood mononuclear cells. Present study has been conducted to clarify how this short mRNA is generated, and demonstrated that a novel 385 bp sequence is located 1.1 kb upstream from the HSP70-1 gene of normal subjects. Except for the 162 bp deletion, it is compatible with part of the 5'-flanking sequence of the HSP70-1 gene, and contains another exon of 358 bp (exon 1) that may be connected to the 3'-terminus (exon 3) of the conventional HSP70-1 gene. Alternative transcription of exons 1 and 3 may cause the short mRNA. It is concluded that HSP70-1 gene is constituted of three exons and may cause alternative splicing.