Molecular cloning of the human mucosal lymphocyte integrin alpha super(E) subunit. Unusual structure and restricted RNA distribution

• Published in: The Journal of biological chemistry 1994-01, Vol.269 (8), p.6016-6025
• Main Authors: Shaw, S K, Cepek, K L, Murphy, E A, Russell, G J, Brenner, M B, Parker, C M
• Format: Article
• Language: English
• Subjects: alpha E subunit; amino acid sequence; cDNA; genes; integrin; lymphocytes T; man; nucleotide sequence; prediction
• ISSN: 0021-9258

The human mucosal lymphocyte-1 (HML-1) antigen is expressed on a subclass of T-lymphocytes known as intra-epithelial lymphocytes which are located between mucosal epithelial cells. The HML-1 complex is known to mediate adhesion of intra-epithelial T-lymphocytes to epithelial cell monolayers in vitro. We and others have shown that the HML-1 antigen is an integrin composed of the beta sub(7) subunit in association with a novel alpha subunit, alpha super(E). Here we report the cloning of the alpha super(E) cDNA and its primary amino acid sequence. alpha super(E) contained an inserted or I domain and was more homologous to the other I domain containing integrins than to the cleaved group of integrin alpha subunits. However, alpha super(E) contained a unique extra domain of 55 amino acids located just NH sub(2)-terminal to the I domain without counterpart in other integrins. This extra domain contained a stretch of 18 consecutive charged residues and included a proteolytic cleavage site. Thus alpha super(E) is the only I domain containing integrin alpha subunit that is also cleaved, and the cleavage site is distinct from that of members of the cleaved group of integrin alpha subunits.