Molecular Cloning and Characterization of a Second Subunit of the Interleukin 1 Receptor Complex (*)
- Scott A. Greenfeder(1)(§),
- Perla Nunes(1),
- Lia Kwee(2),
- Mark Labow(2),
- Richard A. Chizzonite(1) and
- Grace Ju(1)(¶)
- From the (1) Departments of Inflammation/Autoimmune Diseases and
- (2) Biotechnology, Roche Research Center, Hoffmann-La Roche Inc., Nutley, New Jersey 07110
- ¶ To whom correspondence should be addressed. Tel.: 201-235-5621; Fax: 201-235-5046.
Abstract
A monoclonal antibody (mAb) was isolated that blocked the binding and bioactivity of both human and murine interleukin 1β
(IL-1β) on murine IL-1 receptor-bearing cells. This mAb recognized a protein that was distinct from the Type I and Type II
IL-1 receptors, suggesting that an additional protein exists that is involved in IL-1 biological responses. By expression
cloning in COS-7 cells, we have isolated a cDNA from mouse 3T3-LI cells encoding this putative auxiliary molecule, which we
term the IL-1 receptor accessory protein (IL-1R AcP). Sequence analysis of the cDNA predicts an open reading frame that encodes
a 570-amino acid protein with a molecular mass of 
66 kDa. The IL-1R AcP is a member of the Ig superfamily by analysis of its putative extracellular domain and also bears limited
homology throughout the protein to both Type I and Type II IL-1 receptors. Northern analysis reveals that murine IL-1R AcP
mRNA is expressed in many tissues and appears to be regulated by IL-1. In mammalian cells expressing natural or recombinant
Type I IL-1R and IL-1R AcP, the accessory protein forms a complex with the Type I IL-1R and either IL-1α or IL-1β but not
IL-1ra. The recombinant accessory protein also increases the binding affinity of the recombinant Type I IL-1R for IL-1β when
the two receptor proteins are coexpressed. Therefore, the functional IL-1 receptor appears to be a complex composed of at
least two subunits.
Footnotes
-
↵* The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The nucleotide sequence(s) reported in this paper has been submitted to the GenBank
/EMBL Data Bank with accession number(s) X85999.
-
↵1 The abbreviations used are:
- IL-1
-
interleukin 1
- IL-1α
-
interleukin 1α
- IL-1β
-
interleukin 1β
- IL-1ra
-
interleukin 1 receptor antagonist
- IL-1R
-
interleukin 1 receptor
- IL-1R AcP
-
interleukin 1 receptor accessory protein
- smuIL-1R AcP
-
soluble murine IL-1R AcP
- CHO
-
Chinese hamster ovary
- mu
-
murine
- hu
-
human
- PAGE
-
polyacrylamide gel electrophoresis
- ORF
-
open reading frame
- mAb
-
monoclonal antibody
- EF
-
elongation factor
- DMEM
-
Dulbecco's modified Eagle's medium
- FCS
-
fetal calf serum
- PBS
-
phosphate-buffered saline
- kb
-
kilobase(s)
- bp
-
base pair(s).
-
↵2R. A. Chizzonite, unpublished data.
-
↵3R. A. Chizzonite, T. P. Truitt, R. Semionow, M. P. Setteducato, P. Nunes, and A. S. Stern, manuscript in preparation.
-
↵4A. Stern, W. Levin, and R. A. Chizzonite, unpublished data.
-
↵5E. Labriola-Tompkins and G. Ju, manuscript in preparation.
- © 1995 by The American Society for Biochemistry and Molecular Biology, Inc.
