Table 1.
Selectivity of −S4 β-neurexins and +B neuroligin for glutamatergic synapses, and +S4 β-neurexins and −B neuroligins for GABAergic synapses
A. Effect of splicing on relative binding affinitiesa | ||||
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B. Induction of postsynaptic protein clustering by +S4 neurexin 1β in co-culture assaysb | ||||
Proteins: | Neuroligin 1/3/4 | Neuroligin 2 | PSD-95 | Gephyrin |
Clustering (%): | 65c | 90c | 50c, 7d | 104c, 110d |
C. Enhancement of selective presynaptic input onto neurons by overexpression of neuroligin variantse | ||||
Neuroligin 1 +B | Neuroligin 1 −B | Neuroligin 2 (always −B) | ||
Enhancement of VGlut1: | 4.7d, 1.5f | 2.5d | 5.3d, 1.5f | |
Enhancement of VGAT: | 1.5d, 2.2f | 5.0d | 5.6d, 3.0f |
Line widths reflect affinity of interaction. β-Neurexins that contain an insert at site 4 (+S4) interact preferentially with neuroligins that lack an insert at the B site (−B); they have lower affinity for +B neuroligin. β-Neurexins that lack an insert at site 4 (−S4) interact with −B neuroligins and +B neuroligin with equal affinity [9••,43••,44••].
Induction is reported normalized to 100% induction by neurexin 1β (−S4).
From [9••].
From [44••].
Enhancement is reported as increased density of inputs immunoreactive for VGlut (a marker of glutamatergic presynapses) or VGAT (a marker of GABAergic presynapses) relative to a value of 1.0 for control input density onto neurons expressing enhanced green fluorescent protein (EGFP). The neuroligin forms tested all contained the A-site insert.
From [35].