CLONING AND CHARACTERIZATION OF ALPHA(PS1), A NOVEL DROSOPHILA-MELANOGASTER INTEGRIN

The Drosophila position-specific integrins (PS integrins or PS antigens) comprise two heterodimeric complexes, alpha(PS1)beta(PS) and alpha(PS2)beta(PS). With the cloning of alpha(PS1), described here, we complete the characterization of the primary structure of the three PS integrin subunits. We have purified the alpha(PS1) subunit, obtained peptide sequence and isolated genomic and cDNA clones. The encoded alpha(PS1) protein contains the cysteine pattern of the cleaved alpha integrins, three putative metal binding domains and shows the other characteristic features of alpha integrins. Regions of sequence variation indicate that alpha(PS1) is distinct from all other alpha chains. The transcript analysis shows that the patterns of both alpha(PS1) mRNA and protein expression are the same, suggesting that the gene is controlled transcriptionally. We compare the gene structures of the Drosophila alpha(PS1), alpha(PS2), the human alpha(IIb) and alpha(X) (p150,95) and the C elegans F54G8.3 integrins. We find several positions and phases of introns conserved which, supported by conservation also in the amino acid sequence, indicates that they all derive from a common ancestral gene.