cDNA heterogeneity suggests structural variants related to the high-affinity IgE receptor.

AUTOR(ES)

Liu, F T

RESUMO

The high-affinity IgE receptor present on mast cells and basophils is responsible for the IgE-mediated activation of these cells. The current model for this receptor depicts a four-subunit structure, alpha beta gamma 2. A cDNA for the alpha subunit was recently cloned and predicts a structure consisting of two homologous extracellular domains, a transmembrane segment, and a cytoplasmic tail. Using a synthetic oligonucleotide corresponding to the amino-terminal sequence of the alpha subunit, we identified a number of cDNA clones from a rat basophilic leukemia cell cDNA library. Nucleotide sequencing established four different forms of cDNA: one is nearly identical to the published cDNA; the second differs from the first in the 5' untranslated sequence; the other two forms use either one or the other of the 5'-end sequences as above and lack 163 base pairs in the region coding for the second extracellular domain. RNase protection analysis with radioactive RNA probes established the heterogeneity of rat basophilic leukemia cell mRNA with regard to both the 5' and the internal sequences. Our results suggest the existence of at least four different protein forms related to the alpha subunit of the high-affinity IgE receptor.

Documentos Relacionados

• Association of the high-affinity receptor for IgG (Fc gamma RI) with the gamma subunit of the IgE receptor.
• Transmembrane signaling by the high-affinity IgE receptor on membrane preparations.
• Physical association between the high-affinity IgG receptor (Fc gamma RI) and the gamma subunit of the high-affinity IgE receptor (Fc epsilon RI gamma).
• The high-affinity IgE receptor (FcεRI) blocks apoptosis in normal human monocytes
• Stable “zeta” peptides that act as potent antagonists of the high-affinity IgE receptor