Partial purification and characterization of formylpeptide receptor from rabbit peritoneal neutrophils

The formylpeptide receptors from 40 X 10(9) cells of rabbit peritoneal neutrophils have been solubilized with digitonin and partially purified by sequential fMet-Leu-Phe-Sepharose affinity and wheat-germ agglutinin agarose affinity chromatography. The binding activity of the receptor toward [3H]fNle-Leu-Phe is difficult to restore fully after elution of the receptor from the fMet-Leu-Phe-Sepharose affinity column. A 2,000-fold purification of the receptor from the particulate fraction is achieved with a yield of about 23%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Coomasie blue or silver staining of purified receptor preparations reveal a major polypeptide with an apparent Mr (50,000-70,000) and isoelectric points (pl 6.0-6.5) that coincides with the polypeptide labeled by the specific affinity cross-linking probe for formylpeptide receptor (125I-hexapeptide). The receptor has an apparent Stokes radius of 47 A when analyzed by gel filtration chromatography. Using synthetic peptides poly(Glu-Tyr) (4:1) as the substrates, a membrane-associated tyrosine protein kinase activity is detected and can be solubilized by digitonin. Subsequent analysis indicates that the tyrosine kinase activity is not derived from the receptor.