Article Abstract:
A 2.85 Angstrom-resolution crystal structure of the 55 kd tumor necrosis factor (TNF)-human TNFbeta complex was obtained using the heavy atom multiple isomorphous replacement method combined with solvent flattening. Structural analysis of the molecule indicates a complex comprising of three receptor molecules symmetrically bound to one TNFbeta trimer. The receptor fragment is an end to end assembly of four similar folding domains that binds in the groove between two adjacent TNFbeta subunits. It is propsed that this structure reflects the activation state of the TNF receptor at the cell surface and provides a model for TNF signal generation.
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Article Abstract:
The cytoplasmic C-terminus of Epstein-Barr virus (EBV) latent infection membrane protein (LMP1) associates with a human protein, LMP1-associated protein 1 (LAP1), and with the EB 16 protein. LAP1 is homologous to tumor necrosis factor receptor (TNFR)-associated factor 2, while the EB 16 protein, is homologous to human TNFR-associated protein. Colocalization of EB16 and LAP1 proteins occurs due to LMP1 expression in the LMP1 clusters in the plasma membranes of lymphoblasts. The binding between LMP1 and p80 TNFR, and lymphotoxin-beta receptor and CD40 indicates their contribution to cellular signaling pathways.
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Article Abstract:
The transmembrane form of tumor necrosis factor (mTNF) activates the 80 kDa tumor necrosis factor receptor (TNFR(sub 80)) and changes the cell's phenotype. These changes include making TNF-resistant cells sensitive to TNF. The stimulatory activity of mTNF is stronger than that of soluble TNF. Cooperativity between the two receptors increases the cellular response to TNF as mTNF also activates TNFR(sub 60).
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