Differences in phosphorylation of formylpeptide and C5a chemoattractant receptors correlate with differences in desensitization.

Published

Journal Article

To define the regulation of chemoattractant receptors, epitope-tagged human formyl peptide and C5a receptor cDNAs (ET-FR and ET-C5aR) were stably expressed in rat basophilic leukemia, RBL-2H3 cells. An antibody (12CA5) specific to "ET" was used to immunoprecipitate ET-FR and ET-C5aR. fMLP and C5a caused time- and dose-dependent phosphorylation of their respective receptors. Phosphorylated ET-FR migrated as a single broad band between 50 and 70 kDa on SDS-polyacrylamide gel electrophoresis, whereas ET-C5aR exhibited both fast (39-45 kDa) and broadly (39-52 kDa) migrating forms. Fast form phosphorylation alone was observed at low concentrations of C5a (0.001-0.01 microM), or at early times (5-30 s) with a higher concentration of C5a (0.1 microM). Phorbol 12-myristate 13-acetate, thrombin, or antigen caused no phosphorylation of ET-FR but stimulated exclusively fast form phosphorylation of ET-C5aR. The protein kinase C inhibitor staurosporine did not inhibit phosphorylation of ET-FR but blocked the fast migrating component of phosphorylated ET-C5aR. Homologous desensitization correlated with ligand-induced phosphorylation of both receptors. Of note, ET-C5aR but not ET-FR underwent heterologous desensitization by antigen, phorbol 12-myristate 13-acetate, and thrombin. The data suggest that protein kinase C mediates heterologous phosphorylation and desensitization of C5aR but not FR, yet, both receptors are homologously desensitized by a staurosporine-resistant kinase.

Full Text

Duke Authors

Cited Authors

  • Ali, H; Richardson, RM; Tomhave, ED; Didsbury, JR; Snyderman, R

Published Date

  • November 1993

Published In

Volume / Issue

  • 268 / 32

Start / End Page

  • 24247 - 24254

PubMed ID

  • 8226971

Pubmed Central ID

  • 8226971

Electronic International Standard Serial Number (EISSN)

  • 1083-351X

International Standard Serial Number (ISSN)

  • 0021-9258

Language

  • eng