Transforming growth factor beta (TGFβ) receptors are single pass serine/threonine kinase receptors. They exist in several different isoforms that can be homo- or heterodimeric.Three TGFβ superfamily receptors specific for TGFβ, the TGFβ receptors, can be distinguished by their structural and functional properties. TGFβR1 (ALK5) and TGFβR2 have similar ligand-binding affinities and can be distinguished from each other only by peptide mapping. Both TGFβR1 and TGFβR2 have a high affinity for TGFβ1 and low affinity for TGFβ2. TGFβR3 (β-glycan) has a high affinity for both homodimeric TGFβ1 and TGFβ2 and in addition the heterodimer TGF-β1.2. The TGFβ receptors also bind TGFβ3.