title: Identification of the alpha IIb beta 3 integrin in murine tumor cells.
abstract: Previously, we have identified an alpha IIb beta 3-like integrin in tumor cells by using antibodies against platelet alpha IIb beta 3. However, alpha IIb beta 3 was considered to be expressed strictly in megakaryocyte lineage cells. In order to resolve this controversy, the alpha IIb beta 3-like integrin in murine B16 amelanotic melanoma (B16a) cells was characterized at DNA, RNA, and protein levels. The presence of alpha 5, alpha v, alpha IIb, beta 1, and beta 3 genes in B16a cells was confirmed by Southern analysis. mRNAs for all these integrins except alpha v were detectable by Northern blotting. The alpha IIb beta 3 protein was identified by Western blotting using subunit-specific antibodies and by immunoprecipitation using complex-specific antibody. The alpha IIb beta 3 integrin was localized intracellularly by immunocytochemistry. Finally, alpha IIb and beta 3 mRNAs were amplified by reverse transcription-polymerase chain reaction and the identity of alpha IIb was verified by sequencing. Partial DNA and deduced amino acid sequence analysis showed that B16a alpha IIb shares approximately 80% homology with the human alpha IIb and approximately 90% homology with the rat alpha IIb, whereas B16a alpha IIb shares only approximately 26% homology with the human alpha v. These experiments indicate that the alpha IIb beta 3-like protein in B16a cells is the authentic alpha IIb beta 3 and demonstrate, for the first time, that integrin alpha IIb beta 3 is not confined to megakaryocyte lineage cells.
authors.affiliation: Department of Radiation Oncology, Wayne State University, Detroit, Michigan 48202.
authors.forename: Y Q
authors.initials: YQ
authors.lastname: Chen
authors.forename: X
authors.initials: X
authors.lastname: Gao
authors.forename: J
authors.initials: J
authors.lastname: Timar
authors.forename: D
authors.initials: D
authors.lastname: Tang
authors.forename: I M
authors.initials: IM
authors.lastname: Grossi
authors.forename: M
authors.initials: M
authors.lastname: Chelladurai
authors.forename: T J
authors.initials: TJ
authors.lastname: Kunicki
authors.forename: S E
authors.initials: SE
authors.lastname: Fligiel
authors.forename: J D
authors.initials: JD
authors.lastname: Taylor
authors.forename: K V
authors.initials: KV
authors.lastname: Honn
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001792:Blood Platelets / Q000502:physiology*; D015153:Blotting, Western; D015342:DNA Probes; D006801:Humans; D016023:Integrins / Q000032:analysis* / Q000235:genetics*; D046911:Macromolecular Substances; D008546:Melanoma, Experimental / Q000235:genetics / Q000648:ultrastructure; D051379:Mice; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D012689:Sequence Homology, Nucleic Acid; D014407:Tumor Cells, Cultured
chemical_list: D015342:DNA Probes; D016023:Integrins; D046911:Macromolecular Substances