The RUNX1/ETO complex consists of the E box binding transcription factors HEB and LYL1 and the bridging factors LMO2 and LDB1.
Also other complement activating molecules (MBL, ficolins, natural antibodies and surfactant proteins), C-reactive protein, annexins and thrombospondin-1 have been described to act as bridging factors.
If the octamer motif is at a distal site, the protein requires stem-cell-specific bridging factors that link it to the transcription initiation site [ 15].
A similar scenario has been described for other transcriptional co-activators that exert an effect as bridging factors to build the transcriptional activator complex (Valineva et al, 2005).
Whether substrate-specific bridging factors are required for the diverse functions of Elongin-Cullin complex es), and for Cullin-type E3 ligases in general, is an intriguing possibility that deserves further investigation.
If each independent mutation reduces the affinity for one or more potential bridging factors, simultaneous mutation of the TEN-domain and the TEL-patch should lead to an additive reduction of the fraction of nuclei that show co-localization of telomerase and OB-fold foci.
For example, TLR4 stimulation by lipopolysaccharide induces the recruitment of Toll/IL-1 receptor adaptor protein (also referred to as Mal) and TRIF-related adaptor molecule (TRAM), which most probably serve as bridging factors to recruit myeloid differentiation primary response gene 88 (MyD88) and TIR domain-containing adaptor-inducing IFNβ (TRIF), respectively.
The dimensionless bridging factor is calculated by the normalized bridging stress intensity factor with respect to the remote stress intensity factor.
Chang and Yang (2008) examined fatigue crack growth in Glare by modulating the stress intensity parameter with a bridging factor and obtained the S-N curve based on the initiation and growth life of the crack.
An analytical approach was used for predicting the crack growth rate with an empirical Paris-type equation, where the effective stress intensity factor in the metal layer is modulated by a bridging factor.
