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Reconstitution and transphosphorylation of TGF‐beta receptor complexes.
Author(s) -
Ventura F.,
Doody J.,
Liu F.,
Wrana J.L.,
Massagué J.
Publication year - 1994
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1994.tb06895.x
Subject(s) - cancer , biology , cancer genetics , genetics , library science , computer science
Transforming growth factor‐beta (TGF‐beta) signals by contacting two distantly related transmembrane serine/threonine kinases called receptors I (T beta R‐I) and II (T beta R‐II). TGF‐beta binds to T beta R‐II, which is a constitutively active kinase and this complex recruits T beta R‐I, causing its phosphorylation and signal propagation to downstream substrates. The biochemical properties of this interaction were analyzed with reconstituted receptor systems. T beta R‐I and T beta R‐II baculovirally expressed at high levels in insect cells have the ligand binding properties of receptors expressed in mammalian cells, and form a complex in which T beta R‐I phosphorylation is dependent on the kinase activity of T beta R‐II. Furthermore, T beta R‐I and T beta R‐II can form a complex in vitro, and their cytoplasmic domains can specifically interact in a yeast two‐hybrid system. In vitro complex formation with catalytically active T beta R‐II is necessary and sufficient for T beta R‐I phosphorylation, which within this complex does not require the catalytic activity of T beta R‐I, thus mimicking T beta R‐I phosphorylation in intact cells. In addition, T beta R‐I phosphorylated in vitro remains associated with T beta R‐II. These results suggest that T beta R‐I and T beta R‐II have affinity for each other, however, the ligand is required for stable complex formation under physiological conditions. Once formed, this complex is sufficient for T beta R‐I phosphorylation by T beta R‐II.