The C-terminus of CIS defines its interaction pattern.
Proteins of the SOCS (suppressors of cytokine signalling) family are characterized by a conserved modular structure with pre-SH2 (Src homology 2), SH2 and SOCS-box domains. Several members, including CIS (cytokine-inducible SH2 protein), SOCS1 and SOCS3, are induced rapidly upon cytokine receptor activation and function in a negative-feedback loop, attenuating signalling at the receptor level. We used a recently developed mammalian two-hybrid system [MAPPIT (mammalian protein-protein interaction trap)] to analyse SOCS protein-interaction patterns in intact cells, allowing direct comparison with biological function. We find that, besides the SH2 domain, the C-terminal part of the CIS SOCS-box is required for functional interaction with the cytokine receptor motifs examined, but not with the N-terminal death domain of the TLR (Toll-like receptor) adaptor MyD88. Mutagenesis revealed that one single tyrosine residue at position 253 is a critical binding determinant. In contrast, substrate binding by the highly related SOCS2 protein, and also by SOCS1 and SOCS3, does not require their SOCS-box.
Lavens
Delphine
D
Flanders Interuniversity Institute for Biotechnology, Department of Medical Protein Research (VIB09), Faculty of Medicine and Health Sciences, Ghent University, Baertsoenkaai 3, 9000 Ghent, Belgium.
Ulrichts
Peter
P
Catteeuw
Dominiek
D
Gevaert
Kris
K
Vandekerckhove
Joël
J
Peelman
Frank
F
Eyckerman
Sven
S
Tavernier
Jan
J
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002846:Chromatography, Affinity; D017931:DNA Primers; D018076:DNA, Complementary / Q000235:genetics; D006801:Humans; D007668:Kidney; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010748:Phosphopeptides / Q000737:chemistry / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D050826:Suppressor of Cytokine Signaling Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
D017931:DNA Primers; D018076:DNA, Complementary; D010446:Peptide Fragments; D010748:Phosphopeptides; D011994:Recombinant Proteins; D050826:Suppressor of Cytokine Signaling Proteins