Cloning and Characterization of a Novel β Integrin-Related cDNA Coding for the Protein TIED (“Ten β Integrin EGF-like Repeat Domains”) That Maps to Chromosome Band 13q33: A Divergent Stand-Alone Integrin Stalk Structure

Abstract

Herein we describe the cDNA sequence of a novel human gene,ITGBL1,encoding a β integrin-related protein termed TIED [for ten β integrin epidermal growth factor (EGF)-like repeat domains]. Overlapping cDNA clones from fetal lung, HUVEC, and osteoblast cDNA libraries encode a sequence comprising a typical signal peptide, followed by a hydrophilic 471-amino-acid domain containing 10 tandem EGF-like repeats strikingly similar to those found in the cysteine-rich “stalk-like” structure of integrin β subunits. The EGF-like repeats of TIED and β integrins are unique in that they alternate in homology and possess two additional cysteines (eight in total) whose positions differ from those in the other eight-cysteine EGF-like domains of laminin, fibrillin, and the latent TGF-β binding proteins. TIED mRNA transcripts of 2.8 kb were detected in aorta, thymus, and osteogenic sarcoma cells. TheITGBL1gene was mapped to human chromosome 13, band 13q33. We suggest thatITGBL1may be linked in some way with the evolution of the integrin β subunits.