Structure of the bovine tau gene: alternatively spliced transcripts generate a protein family.

Tau, a major class of microtubule-associated proteins, consists of a family of proteins that are heterogeneous in molecular weight. The presence of internal deletions in previously described cDNA clones for murine and bovine tau suggested that alternative splicing of transcripts could account for the protein size heterogeneity. Analysis of the exon-intron structure of the bovine tau gene provided sequence information necessary to detect new variants of tau transcripts by in vitro amplification techniques. The variant transcripts found corresponded to mRNA species missing one or more exons, which suggested that by skipping various exons during mRNA splicing, a family of proteins is generated. Four major tau protein isoforms isolated from bovine brain were identified by comparison with translation products of cDNA constructs and the use of antisera raised against synthetic peptides. These studies provide reagents and a basis for analyzing potentially altered forms of tau proteins in brains of patients with Alzheimer's disease.