Figure 5.

Canonical TGFβ signaling mediated by TGFβ co-receptor betaglycan and soluble betaglycan formed after proteolytic cleavage. TGFβ ligands presentation to the dedicated TGFβRs includes the formation of a binary complex between betaglycan and TGFβ dimer, which potentiates binding of TGFβRIIs. In turn, once bound, TGFβRIIs lead to recruitment of TGFβRIs, with a simultaneous displacement of betaglycan from signaling complex. Betaglycan can also modulate TGFβ signaling due to its ectodomain shedding. A soluble form of betaglycan effectively sequestrates TGFβ dimers, thus diminishing pathway activation.