AMINO-ACIDS 327-350 OF THE HUMAN C5A-RECEPTOR ARE NOT ESSENTIAL FOR [I-125] C5A BINDING IN COS CELLS AND SIGNAL-TRANSDUCTION IN XENOPUS-OOCYTES

The anaphylatoxic peptide C5a is an important inflammatory mediator of the complement system. We have generated human C5a-receptor (hC5aR) m utants with truncation of its cytosolic carboxyl-terminus (C-terminus) . Both mutants were analysed for C5a-binding in transiently expressing COS cells, and one mutant additionally for GTP-binding regulatory pro tein (G-protein) coupling in cRNA-injected Xenopus oocytes. Our data s uggest that (a) amino acids (aa) 314 to 326 as part of the C-terminus are necessary for proper receptor folding or expression and (b) the re ceptor C-terminus distal from position 327 is not critical for recepto r expression, folding, binding and G-protein coupling.