Previously, we have identified an α(IIb)β3-like integrin in tumor cells by using antibodies against platelet α(IIb)β3. However, α(IIb)β3 was considered to be expressed strictly in megakaryocyte lineage cells. In order to resolve this controversy, the α(IIb)β3-like integrin in murine B16 amelanotic melanoma (B16a) cells was characterized at DNA, RNA, and protein levels. The presence of α5, α(v), α(IIb), β1 and β3 genes in B16a cells was confirmed by Southern analysis. mRNAs for all these integrins except α(v) were detectable by Northern blotting. The α(IIb)β3 protein was identified by Western blotting using subunit-specific antibodies and by immunoprecipitation using complex-specific antibody. The α(IIb)β3 integrin was localized intracellularly by immunocytochemistry. Finally, α(IIb) and β3 mRNAs were amplified by reverse transcription-polymerase chain reaction and the identity of α(IIb) was verified by sequencing. Partial DNA and deduced amino acid sequence analysis showed that B16a α(IIb) shares ~80% homology with the human α(IIb) and ~90% homology with the rat α(IIb), whereas B16a α(IIb) shares only ~26% homology with the human α(v). These experiments indicate that the α(IIb)β3-like protein in B16a cells is the authentic α(IIb)β3 and demonstrate, for the first time, that integrin α(IIb)β3 is not confined to megakaryocyte lineage cells.
|Number of pages||7|
|Journal||Journal of Biological Chemistry|
|Publication status||Published - Jan 1 1992|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology