The N-terminal bHLH and PAS domain of HIF-1α and HIF-1β mediates heterodimerization and DNA binding [14].
Recent findings showed instead that the N-myc leucine zipper mediates exclusively heterodimerization with other binding partners [28], [29].
A consensus of their study is that Ste11 SAM domains form tight homodimers or high-order oligomers, whereas the Ste50 SAM domain, with a slightly different sequence, is largely monomeric in solution but can mediate strong heterodimerization with the Ste11 SAM domain [17], [18], [20], [21].
In addition to mediating heterodimerization of bHLH-PAS proteins, PAS domains can also recruit regulatory proteins to control transcription.
Interestingly, Fbxw8 was discovered to mediate heterodimerization of CRL1 and CRL7 forming a high-order ubiquitin ligase complex that plays a role in placental development [ 86].
By contrast, CLOCK and BMAL1 are defined by their tandem PAS domains, which mediate heterodimerization, and disordered C-termini that regulate their activity.
As we had ascertained that recombinant Nt-KH1 of either FMRP or of FXR1P was not able to homodimerize at low concentrations, we investigated whether Nt-KH1 could mediate heterodimerization of the two proteins in vitro.
Among ErbB family members, ErbB1 and ErbB4 are fully functional receptor tyrosine kinases, whereas ErbB2 does not bind any known ligand and ErbB3 has no intrinsic kinase activity, however, ErbB3 still mediate signaling by heterodimerization with other receptors of the family [22].
In these studies, we used a rapamycin-mediated heterodimerization system combined with PFC to confer temporal control to TEVp activity.
