A new isoform of human membrane-bound IgE.
The epsilon-chain of membrane-bound IgE on the surface of B lymphocytes is known to contain a membrane-anchoring peptide segment that is encoded by two membrane exons, me.1 and me.2. In analyzing pertinent segments in mRNA from human IgE-expressing B cells by using PCR methods and Northern blotting analyses, we have identified three species of mRNA of epsilon-chain with variations in the splicing of the membrane exons. The conventional species (m/s) contains the predicted me.1 and me.2; species m/1 harbors 156 extra nucleotides 5' of me.1 with unaltered reading frame; species s/t lacks me.1 and hence the segment encoding the hydrophobic transmembrane stretch and contains a shifted me.2 reading frame. Rabbit antibodies, which were prepared by immunization using a peptide of 36 amino acid residues representing an encoded segment unique to mRNA species m/l, could specifically bind to human IgE-expressing B cell lines and react with an epsilon-chain on Western immunoblots. These results indicate that there exists a previously unidentified isoform of human membrane-bound IgE.
Peng
C
C
Tanox Biosystems, Inc., Houston, TX 77025.
Davis
F M
FM
Sun
L K
LK
Liou
R S
RS
Kim
Y W
YW
Chang
T W
TW
D000595:Amino Acid Sequence; D001402:B-Lymphocytes / Q000502:physiology; D001483:Base Sequence; D015152:Blotting, Northern; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry; D005091:Exons; D015870:Gene Expression; D005803:Genes, Immunoglobulin; D006801:Humans; D007073:Immunoglobulin E / Q000737:chemistry / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D016133:Polymerase Chain Reaction; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics
D008565:Membrane Proteins; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D007073:Immunoglobulin E