TGFβ receptors are single pass serine/threonine kinase receptors. They exist in several different isoforms that can be homo- or heterodimeric. The number of characterized ligands in the TGFβ superfamily far exceeds the number of known receptors, suggesting the promiscuity that exists between the ligand and receptor interactions.
Three TGF-β receptor types can be distinguished by their structural and functional properties. Receptor types I and II have similar ligand-binding affinities and can be distinguished from each other only by peptide mapping. Both receptor types I and II have a high affinity for TGF-β1 and low affinity for TGF-β2. TGF-β receptor type III has a high affinity for both TGF-β1 and -β2 and in addition TGF-β1.2.
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