Requirement of the cytoplasmic portion for dimer formation of Fcalpha/micro receptor expressed on cell surface.
Fcalpha/mu receptor (Fcalpha/muR), an Fc receptor for IgA and IgM, is the only Fc receptor for IgM identified on hematopoietic cells in human and rodents and for IgA in rodents. Fcalpha/microR is a type 1 transmembrane protein containing one immunoglobulin-like domain in the extracellular portion. Both human and mouse Fcalpha/microR mediate endocytosis of the ligands IgA and IgM, for which the cytoplasmic portion of Fcalpha/microR is responsible. However, molecular characteristics of Fcalpha/muR involved in the function have been incompletely understood. Here, we show that both monomeric and dimeric Fcalpha/microR are expressed in a mouse B cell line BCL1-B20 and BW5147 or Ba/F3 transfectants stably expressing Fcalpha/microR. We also show that the dimeric, but not monomeric, Fcalpha/microR is preferentially localized to the cell surface of the transfectants. BW5147 transfectant expressing mutant Fcalpha/microR lacking the cytoplasmic portion expressed only the monomeric Fcalpha/microR. These results suggest that the cytoplasmic portion is required for the dimer formation and thus for efficient cell surface expression of Fcalpha/microR.
Cho
Yukiko
Y
Department of Immunology, Institute of Basic Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Ten-nohdai, Tsukuba, Ibaraki 305-8575, Japan.
Honda
Shin-ichiro
S
Yoshizawa
Yuichi
Y
Takagaki
Kana
K
Usui
Kenta
K
Shibuya
Akira
A
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D051379:Mice; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D055503:Protein Multimerization; D011961:Receptors, Fc / Q000737:chemistry* / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014162:Transfection
D008024:Ligands; D050505:Mutant Proteins; D011961:Receptors, Fc