Cloning and characterization of a mouse IL-12 receptor-beta component.
Using DNA cross-hybridization, we have isolated and characterized cDNA clones encoding a mouse (mo) IL-12R beta component. Two forms of cDNA were found. The first form encodes a receptor protein that has an overall structure very similar to that of the known human (hu) IL-12R beta with 54% amino acid identity, whereas in the second type of mouse cDNA, the equivalent of the transmembrane region has been deleted. This presumed alternative splicing event also gives rise to a frame shift that results in a receptor with an identical extracellular domain but a different C-terminal sequence. Whether this alternative C terminus is capable of signaling is not yet known. Both types of receptors when expressed in COS-7 cells are membrane associated and bind moIL-12 with an affinity of 1 nM, similar to the affinity of huIL-12R beta for huIL-12. The monomeric size of both moIL-12R beta proteins is about 100 kDa. Similar to huIL-12R beta, moIL-12R beta is expressed at the surface of COS-7 and Ba/F3 cells as a dimer/oligomer whose formation is independent of IL-12 binding. When expressed in Ba/F3 cells, moIL-12R beta binds moIL-12 with two affinities of 50 and 470 pM, corresponding to the medium and high affinity IL-12 binding sites previously identified on mouse Con A lymphoblasts. Despite the higher affinity displayed by the moIL-12R beta in Ba/F3 cells, this receptor alone is not sufficient to transduce a signal, suggesting that another subunit is probably required to generate a functional moIL-12R complex.
Chua
A O
AO
Department of Inflammation/Autoimmune Diseases, Hoffmann-La Roche Inc., Nutley, NJ 07110, USA.
Wilkinson
V L
VL
Presky
D H
DH
Gubler
U
U
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000302:isolation & purification; D005260:Female; D015698:Genomic Library; D006801:Humans; D018664:Interleukin-12 / Q000276:immunology / Q000378:metabolism; D046911:Macromolecular Substances; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D011485:Protein Binding; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011917:Rats, Inbred Lew; D018123:Receptors, Interleukin / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification*; D053707:Receptors, Interleukin-12
D018076:DNA, Complementary; C508444:Il12rb2 protein, rat; D046911:Macromolecular Substances; D012333:RNA, Messenger; D018123:Receptors, Interleukin; D053707:Receptors, Interleukin-12; D018664:Interleukin-12