If membranes are more completely solubilized in octyl glucoside and then exchanged into Triton X-100, FPR is found in tight association with a protein immunologically related to actin.
Receptor also binds to immobilized rabbit actin or free neutrophil cytosolic actin.
Most recently, we have identified two proteins of molecular weight 45 and 40 kDa that appear to crosslink to the agonist occupied FPR, forming complexes of 110 and 150 kDa. The 110 kDa species appears when receptor is not associated with G protein, but is more efficiently crosslinked in the presence of Gi2 . We surmise that the 45 and 40 kDa species may be actin and Gia, respectively. Studies are underway to confirm the identity of these species and a function for the FPR actin complexes. Model of regulatory interactions of FPR with G proteins and actin.