Identification of a functional site on the type I TGF-beta receptor by mutational analysis of its ectodomain.
Six charged amino acid residues located in the ectodomain of the full-length type I transforming growth factor (TGF)-beta receptor were individually mutated to alanine. Mutation of residues D47, D98, K102 and E104 resulted in functionally impaired receptors as demonstrated by a marked decrease in ligand-dependent signaling and ligand internalization relative to the wild-type receptor. The other two mutants (K39A and K87A) exhibited wild-type-like activity. Molecular modeling indicates that the four functionally important residues are located on the convex face of the ectodomain structure. Since mutation of these four residues affects signaling and ligand internalization but not ligand binding, we propose that this functional site is an interacting site between type I and II receptors.
Guimond
Alain
A
Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount Avenue, H4P 2R2, Montréal, QC, Canada.
Sulea
Traian
T
Zwaagstra
John C
JC
Ekiel
Irena
I
O'Connor-McCourt
Maureen D
MD
D030201:Activin Receptors, Type I / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D004252:DNA Mutational Analysis; D006801:Humans; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D051381:Rats; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013329:Structure-Activity Relationship
D008024:Ligands; D018125:Receptors, Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; C000625843:Tgfbr1 protein, rat