Neuroligin 4

Nonneuronal ligand for human neuroligin 4 (hNL4) needs identifying, which leads me to raise the following two questions:

1. Is full-length hNL4-as-yet-unidentified ligand complex tetrameric like this model?

2. Can we observe their assembly and measure the binding force between them using AFM in solution?  

Addendum primum:

I have just noticed an article discussing NL’s.