Human IgG Fc receptor (FcγR) cDNA clones were isolated by cross-species hybridization by probing cDNA libraries with the low-affinity FcγR β1 cDNA clone from mouse as well as a pool of oligonucleotides constructed from the nucleotide sequence of this FcγR. Three cDNA clones were isolated and analysis of the predicted amino acid sequence indicated that the human FcγR protein is synthesized with a 34-amino acid leader and the mature protein is composed of 281 amino acids. The extracellular region of this FcγR was divided into two domains, which were very similar to each other and to the corresponding regions of both mouse α and β FcγRs and showed a clear relationship to immunoglobulin variable regions. One possible N-linked glycosylation site was found in each of the extracellular domains. The human FcγR leader sequence was shown to be similar to the mouse α FcγR leader sequence, but the transmembrane region was most similar to the mouse β1 FcγR. The intracellular domain of the human FcγR was surprisingly different from both mouse FcγRs. RNA blot analysis of human cells demonstrated two transcripts (2.5 and 1.5 kilobases) that arise by use of different adenylylation signals. The cellular expression of these transcripts suggests that they encode the low-affinity p40 FcγR protein.
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|Publication status||Published - 1 Dec 1988|
- antigen-antibody receptor
- domain structure
- immunoglobulin gene superfamily
- sequence homology