The Drosophila position-specific integrins (PS integrins or PS antigens) comprise two heterodimeric complexes, αPS1βPS and αPS2βPS. With the cloning of αPS1 described here, we complete the characterization of the primary structure of the three PS integrin subunits. We have purified the αPS1 subunit, obtained peptide sequence and isolated genomic and cDNA clones. The encoded αPS1 protein contains 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 αPS1 is distinct from all other alpha chains. The transcript analysis shows that the patterns of both αPS1 mRNA and protein expression are the same, suggesting that the gene is controlled transcriptionally. We compare the gene structures of the Drosophila αPS1, αPS2, the human αPS1and αPS2 (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.
- Molecular cloning