Identification, in mouse macrophages and in serum, of a soluble receptor for the Fc portion of IgG (Fc gamma R) encoded by an alternatively spliced transcript of the Fc gamma RII gene.
Low affinity Fc gamma R are a heterogeneous group of glycoproteins which exist in transmembrane (TM) as well as in soluble forms. Two membrane isoforms of the murine type II Fc gamma R, Fc gamma RIIb1 and Fc gamma RIIb2, have been described. They result from the translation of alternatively spliced pre-mRNA, Fc gamma RIIb2 lacking sequences of the first intracytoplasmic domain (IC1). Soluble forms of Fc gamma R (sFc gamma R) have previously been shown to result from proteolysis of membrane receptors. We report here the identification, in macrophages, of a mRNA derived from the Fc gamma RII gene by splicing exons encoding the TM and IC1 domains, i.e. corresponding to a TM-deleted Fc gamma RIIb2 mRNA. A soluble protein possibly encoded by this mRNA was identified in macrophage supernatants. In accordance with Fc gamma R nomenclature, we propose to name this new Fc gamma RII isoform Fc gamma RIIb3. It is the most abundant sFc gamma R present in serum, as compared with sFc gamma R resulting from cleavage of membrane Fc gamma R.
Tartour
E
E
INSERM U.255, Institut Curie, Paris, France.
de la Salle
H
H
de la Salle
C
C
Teillaud
C
C
Camoin
L
L
Galinha
A
A
Latour
S
S
Hanau
D
D
Fridman
W H
WH
Sautès
C
C
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D008264:Macrophages / Q000737:chemistry*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D008970:Molecular Weight; D012333:RNA, Messenger / Q000032:analysis; D017452:Receptors, IgG / Q000032:analysis* / Q000235:genetics
D012333:RNA, Messenger; D017452:Receptors, IgG