Altogether the results indicate that neutral membranes are able to interact with Penetratin which confirms that the phosphate negatively charged groups exposed on the external leaflet of plasma membrane are competent for interaction with the basic peptide.
This suggests that the scanning state should be competent for interaction with the SRP receptor, potentially permitting targeting while the TMD is still inside the tunnel.
Thus, displacement of the Ubl domain by phosphoubiquitin binding may lead to exposure of a surface competent for interaction with ubiquitin.
However, HER2 and HER3 are not able to stimulate cell signalling as monomers as HER2 does not possess an ectodomain competent for interaction with any ligand, whereas HER3 lacks the kinase complex [ 7].
The likely role of Thr171 phosphorylation is to orient these five residues so their side-chains are in a binding competent mode for interaction with an unidentified RNA processing factor.
The most likely candidate for driving and subsequently stabilizing the conformational change to a cargo-binding-competent open form is interaction with multiple PtdIns4,5P2 molecules arranged in a roughly planar fashion in the membrane.
In the domain-swapped dimer, the E-helix sequence specifically binds a partner K-helix sequence, whereas in the monomeric form of the protein, the E-helix sequence is unable to fold into a binding-competent conformation and no interaction with the K-helix is seen.
Among the post-synaptic genes present in Amphimedon, many other interaction domains are also conserved making it likely that the ancient signature motifs were competent to interact with ligands.
Upon induction of COX-2 expression, the lncRNA associates with p50, a repressive subunit of NF-κB, and occludes it from the COX-2 promoter, potentially facilitating interaction with activation-competent NF-κB p65/p50 dimers.
We speculate that only oligomeric forms of PAPC transmembrane domains are competent for its interactions with FLRT3 transmembrane domain.
