The Genomic Structure of the Murine α 4,Integrin Gene

The VLA-4 (α₄β₁) integrin is a leukocyte glycoprotein involved in both cell–extracellular matrix and cell–cell interactions. We report here the cloning of the murine α₄ gene whose protein product is antigenically related to the human VLA-4 α chain. The α₄m gene is about 75 kb long and consists of 28 exons, ranging in size from 46 bp (exon 13) to 437 bp (exon 1). The introns varied from 79 bp (intron 8) to more than 17 kb (intron 2). Three mRNA transcripts from this α₄m gene can be visualized on Northern blot. After cloning the 3′ untranslated region (3′ UTR), four polyadenylation sites could be identified, presumably responsible for the presence of three to four transcripts of the α₄ gene, differing substantially in length.