Cloning of cDNA coding for low-affinity Fc receptors for IgE on human T lymphocytes.
Using a cDNA probe corresponding to the membrane-bound form of the B cell receptor for IgE, we have isolated, sequenced, and expressed a cDNA clone which codes for a human T lymphocyte Fc epsilon R from HUT-78 cells. This T cell Fc epsilon R cDNA codes for 320 amino acid residues, and shows high homology to the B cell Fc epsilon R sequence. The major differences between this T cell and the B cell Fc epsilon R cDNA sequences are (i) a limited stretch of nucleotides at the 5' segment of the coding region which encodes a putative cytoplasmic region of the Fc epsilon R molecule and the untranslated 5' end; and (ii) an additional 64 bp segment in the untranslated 3' end containing two repeats in tandem with three existing repeats in the same region. The expression of Fc epsilon R on T lymphocytes may reflect involvement of the Fc epsilon R in regulation of IgE-mediated responses. The cytoplasmic difference implies functional activity of the Fc epsilon R in T lymphocytes that is mechanistically different from the Fc epsilon R of B lymphocytes.
Nonaka
M
M
Division of Immunology, Medical Biology Institute, La Jolla, CA 92037.
Hsu
D K
DK
Hanson
C M
CM
Aosai
F
F
Katz
D H
DH
D000595:Amino Acid Sequence; D000944:Antigens, Differentiation, B-Lymphocyte / Q000235:genetics* / Q000378:metabolism; D001402:B-Lymphocytes / Q000276:immunology; D001483:Base Sequence; D002460:Cell Line; D004247:DNA / Q000235:genetics*; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D011961:Receptors, Fc / Q000235:genetics* / Q000378:metabolism; D017455:Receptors, IgE; D012689:Sequence Homology, Nucleic Acid; D013601:T-Lymphocytes / Q000276:immunology
D000944:Antigens, Differentiation, B-Lymphocyte; D012333:RNA, Messenger; D011961:Receptors, Fc; D017455:Receptors, IgE; D007073:Immunoglobulin E; D004247:DNA