Specific interactions of the autoantigen L7 with multi-zinc finger protein ZNF7 and ribosomal protein S7.

The eucaryotic protein L7, which associates with the large subunit of ribosomes, has been shown to be a major autoantigen in systemic autoimmune arthritis. The N terminus carries a sequence motif that is similar to the leucine zipper domain of eucaryotic transcription factors. This domain promotes the homodimerization of protein ...
L7 through alpha-helical coiled-coil formation and binds to distinct mRNAs, thereby inhibiting their cell-free translation. Using a yeast two-hybrid selection, we have identified from a Jurkat T lymphoma cDNA library ribosomal protein S7 and the multi-zinc finger protein ZNF7 as proteins that interact with protein L7. A fragment of L7 carrying the leucine zipper-like domain is fully sufficient to mediate these interactions. Their potential biological significance is indicated by low apparent dissociation constants of S7-L7 (15 x 10(-9) M) and, respectively, ZNF7-L7 (2 x 10(-9) M) complexes and co-immunoprecipitation of proteins S7, ZNF7, and L7 from a cell lysate with an anti-L7 antibody. We also show that ZNF7-like L7 and S7 can exist in a ribosome-bound form. This study provides further evidence suggesting that L7 is involved in translational regulation through interactions with components of the translational apparatus.
Mesh Terms:
DNA-Binding Proteins, Dimerization, Humans, Jurkat Cells, Kruppel-Like Transcription Factors, Leucine Zippers, Ribosomal Proteins, Ribosomes, Zinc Fingers
J. Biol. Chem.
Date: Aug. 29, 1997
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