Multiple chromatographic forms of the formylpeptide chemoattractant receptor and their relationship to GTP-binding...

The radiolabeled formylpeptide chemoattractant receptor, partially purified by wheat germ agglutinin-Sepharose chromatography, eluted in three distinct peaks when chromatographed on DEAE-Fractogel. Incubation of the lectin-Sepharose purified receptor with 100 microM guanosine 5-(3-O-thio) triphosphate markedly altered the distribution of the radiolabeled receptor when chromatographed on the ion exchange resin. Peaks 2 and 3 were reduced by approximately 50% while peak 1 was concomitantly increased. Western blot analysis revealed the presence of a 40 kDa GTP-binding protein alpha-subunit only in peak 3. Incubation of Western blots with [alpha-32P]GTP detected low molecular mass GTP-binding proteins (24 and 26 kDa) that coeluted with the receptor in peak 2. Incubation of the peak 1 receptor fractions with fractions containing a mixture of GTP binding proteins resulted in the generation of peaks 2 and 3 when chromatographed on DEAE-Fractogel. These results demonstrate that the chromatographic behavior of the formylpeptide receptor is dependent upon its association with GTP binding proteins and that more than one type of GTP-binding protein may be involved.