The use of membrane translocating peptides to identify sites of interaction between the C5a receptor and downstream effector proteins.
The complement fragment C5a is a potent leucocyte chemoattractant and activator, mediating its effects through a G-protein-coupled receptor. Whilst the C-terminal domain of this receptor has been shown to be essential for receptor desensitization and internalization, it is not known which domains couple to the receptor's heterotrimeric G proteins. In this report we have used a membrane translocating sequence (MTS) to examine the effects of the four intracellular domains of the human C5a receptor (C5aR) on the receptor's signalling via G(alphai) family heterotrimeric G proteins in intact RBL-2H3 cells. The results indicate that all of the intracellular domains couple to downstream signalling, with the proximal region of the C terminus being a major binding site and intracellular loop 3 playing a role in G protein activation or receptor desensitization.
Auger
Graham A
GA
Division of Genomic Medicine, The University of Sheffield, Sheffield, UK.
Smith
Brenda M
BM
Pease
James E
JE
Barker
Michael D
MD
D000595:Amino Acid Sequence; D015153:Blotting, Western; D002478:Cells, Cultured; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D044087:Receptor, Anaphylatoxin C5a / Q000235:genetics / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D014178:Translocation, Genetic
D044087:Receptor, Anaphylatoxin C5a; D043562:Receptors, G-Protein-Coupled; D011993:Recombinant Fusion Proteins; D005982:Glutathione Transferase