Table 1. Examples of conformational dependent α₂M activities.

Many of the activities of α₂M are dependent on whether or not the protein is in its native conformation or in its transformed state. Additionally, dissociation of the native α₂M tetramer into dimers (that can be induced using several different chemical methods) has also been demonstrated to influence the activities of α₂M.

Function	Native α2M	Transformed α2M	Dissociated α2M dimer	References
Protease trapping	Yes	No	No*	[21, 66, 67]
Binding to LRP	No	Yes	Yes, providing the treatment does not denature the receptor binding domain* †	[2, 3, 68]
Chaperone activity	Yes	Yes, α2M-protease complexes can also prevent protein aggregation by degrading substrates	Yes, enhanced compared to the native α2M* ‡	[13, 16, 17, 32, 69]
Binding to Aβ1–40 or Aβ1–42 peptide	Yes, but to oligomers only, early on the amyloid forming pathway	Yes, binds monomeric and oligomeric Aβ	Yes, binds monomeric and oligomeric Aβ with higher affinity than native α2M*	[17, 32, 45]
Binding to TGF-β1	Yes; KD = 330 ± 130 nM	Yes; KD = 80 ± 11 nM	Markedly reduced compared to native α2M*	[40, 70]
Binding to TGF-β2	Yes; KD = 11 ± 3 nM	Yes; KD = 13 ± 2 nM	Markedly reduced compared to native α2M*	[40, 70]
Binding to TNF-α	Only weakly; KD > 1.27 ± 0.17 µM	Only weakly; KD > 0.75 ± 0.10 µM	Markedly increased compared to native α2M*	[40, 70]

* α₂M dimers generated by hypochlorite treatment.

† α₂M dimers generated by thiocyanate treatment.

‡ α₂M dimers generated by SDS treatment.